- Versatile synthon for chirally β-deuterated L-amino acids and synthesis of (3R)- and (3S)-[3-2H1]-L-serine
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A divergent and highly enantioselective synthetic methodology for producing chirally β-deuterated L-amino acids was developed. This method is based upon the chirality transcription approach, using diacetone-D-glucos-3- ulose (1) as a template. 3-C-[2-2H1]-Ethenyl-3-O-(N- benzyl)methylthioformimidoyl-D-allo-derivatives (3b and 3c), which are easily accessible from 1, were subjected to halonium ion-assisted cyclization to afford highly diastereoselectively and efficiently versatile 5-membered cyclic carbamate synthons having a stereochemically defined deuterated halomethyl group (4c and 4d, respectively). Subsequent straightforward transformation of these synthons gave rise to (3R)- and (3S)-[3-2H1]-L- serine. Further transformation of the crucial halomethyl group of 4a-c was also pursued to extend this methodology.
- Maeda, Yutaka,Tago, Keiko,Eguchi, Tadashi,Kakinuma, Katsumi
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- Fusaristatin C, a Cyclic Lipodepsipeptide from Pithomyces sp. RKDO 1698
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A new cyclic lipodepsipeptide, fusaristatin C (1), was obtained from the fungus Pithomyces sp. RKDO 1698, which was isolated from the Caribbean octocoral Eunicea fusca. The 2D structure of fusaristatin C was elucidated using NMR spectroscopy and mass spectrometry, while the absolute configuration of the sole chiral amino acid residue (l-serine) was determined using Marfey's method. 3-Hydroxy-2,11-dimethyltetradecanoic acid (HDMT) was cleaved from 1, and the absolute configuration at the C-3 position was determined using Mosher's ester analysis. Subsequent J-based configuration analysis of 1 allowed for assignment of the C-2 configuration. Fusaristatin C exhibited no antimicrobial activity or cytotoxicity.
- MacIntyre, Logan W.,Marchbank, Douglas H.,Correa, Hebelin,Kerr, Russell G.
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- Ruckerbactin Produced by Yersinia ruckeri YRB Is a Diastereomer of the Siderophore Trivanchrobactin Produced by Vibrio campbellii DS40M4
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The Gram-negative bacterium Yersinia ruckeri is the causative agent for enteric red mouth disease in salmonids. The genome of Y. ruckeri YRB contains a biosynthetic gene cluster encoding the biosynthesis of catechol siderophores that are diastereomeric with the known vanchrobactin class of siderophores, (DHBDArgLSer)(1–3). Ruckerbactin (1), produced by Y. ruckeri YRB, was found to be the linear tris-l-serine ester composed of l-arginine and 2,3-dihydroxybenzoic acid, (DHBLArgLSer)3. The biscatechol, (DHBLArgLSer)2 (2), and monocatechol, DHBLArgLSer (3), compounds were also isolated and characterized. The macrolactone of ruckerbactin was not detected. The presence of LArg in ruckerbactin makes it the diastereomer of trivanchrobactin with DArg. The electronic circular dichroism spectra of Fe(III)–ruckerbactin and Fe(III)–trivanchrobactin reveal the opposite enantiomeric configurations at the Fe(III) sites. Fe(III)–ruckerbactin adopts the Δ configuration, and Fe(III)–trivanchrobactin adopts the Λ configuration. Y. ruckeri YRB was also found to produce the antimicrobial agent holomycin (4).
- Butler, Alison,Dulaney, Kalana,Reitz, Zachary L.,Stow, Parker R.,Thomsen, Emil
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p. 264 - 269
(2022/01/15)
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- Leveraging Peptaibol Biosynthetic Promiscuity for Next-Generation Antiplasmodial Therapeutics
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Malaria remains a worldwide threat, afflicting over 200 million people each year. The emergence of drug resistance against existing therapeutics threatens to destabilize global efforts aimed at controlling Plasmodium spp. parasites, which is expected to leave vast portions of humanity unprotected against the disease. To address this need, systematic testing of a fungal natural product extract library assembled through the University of Oklahoma Citizen Science Soil Collection Program has generated an initial set of bioactive extracts that exhibit potent antiplasmodial activity (EC50 25 μM, selectivity index > 250). The unique chemodiversity afforded by these fungal isolates serves to unlock new opportunities for translating peptaibols into a bioactive scaffold worthy of further development.
- Lee, Jin Woo,Collins, Jennifer E.,Wendt, Karen L.,Chakrabarti, Debopam,Cichewicz, Robert H.
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supporting information
p. 503 - 517
(2021/03/01)
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- Targeted Isolation of Asperheptatides from a Coral-Derived Fungus Using LC-MS/MS-Based Molecular Networking and Antitubercular Activities of Modified Cinnamate Derivatives
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Under the guidance of MS/MS-based molecular networking, four new cycloheptapeptides, namely, asperheptatides A-D (1-4), were isolated together with three known analogues, asperversiamide A-C (5-7), from the coral-derived fungus Aspergillus versicolor. The planar structures of the two major compounds, asperheptatides A and B (1 and 2), were determined by comprehensive spectroscopic data analysis. The absolute configurations of the amino acid residues were determined by advanced Marfey's method. The two structurally related trace metabolites, asperheptatides C and D (3 and 4), were characterized by ESI-MS/MS fragmentation methods. A series of new derivatives (8-26) of asperversiamide A (5) were semisynthesized. The antitubercular activities of 1, 2, and 5-26 against Mycobacterium tuberculosis H37Ra were also evaluated. Compounds 9, 13, 23, and 24 showed moderate activities with MIC values of 12.5 μM, representing a potential new class of antitubercular agents.
- Chao, Rong,Hou, Xue-Mei,Xu, Wei-Feng,Hai, Yang,Wei, Mei-Yan,Wang, Chang-Yun,Gu, Yu-Cheng,Shao, Chang-Lun
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- Saccharochelins A-H, Cytotoxic Amphiphilic Siderophores from the Rare Marine Actinomycete Saccharothrix sp. D09
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Siderophores are secreted by microorganisms to survive in iron-depleted conditions, and they also possess tremendous therapeutic potential. Genomic-inspired isolation facilitated the identification of eight amphiphilic siderophores, saccharochelins A-H (1-8), from a rare marine-derived Saccharothrix species. Saccharochelins feature a series of fatty acyl groups appended to the same tetrapeptide skeleton. With the help of gene disruption and heterologous expression, we identified the saccharochelin biosynthetic pathway. The diversity of saccharochelins originates from the flexible specificity of the starter condensation (CS) domain at the beginning of the nonribosomal peptide synthetase (NRPS) toward various fatty acyl substrates. Saccharochelins showed cytotoxicity against several human tumor cell lines, with IC50 values ranging from 2.3 to 17 μM. Additionally, the fatty acid side chains of the saccharochelins remarkably affected the cytotoxicity, suggesting changing the N-terminal acyl groups of lipopeptides may be a promising approach to produce more potent derivatives.
- Bian, Xiaoying,Dai, Guangzhi,Jiao, Nianzhi,Liu, Yang,Ravichandran, Vinothkannan,Ren, Xiangmei,Shen, Qiyao,Sui, Haiyan,Zhang, Youming,Zhong, Lin,Zhou, Haibo
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p. 2149 - 2156
(2021/08/20)
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- Pagoamide A, a Cyclic Depsipeptide Isolated from a Cultured Marine Chlorophyte, Derbesia sp., Using MS/MS-Based Molecular Networking
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A thiazole-containing cyclic depsipeptide with 11 amino acid residues, named pagoamide A (1), was isolated from laboratory cultures of a marine Chlorophyte, Derbesia sp. This green algal sample was collected from America Samoa, and pagoamide A was isolated using guidance by MS/MS-based molecular networking. Cultures were grown in a light- and temperature-controlled environment and harvested after several months of growth. The planar structure of pagoamide A (1) was characterized by detailed 1D and 2D NMR experiments along with MS and UV analysis. The absolute configurations of its amino acid residues were determined by advanced Marfey's analysis following chemical hydrolysis and hydrazinolysis reactions. Two of the residues in pagoamide A (1), phenylalanine and serine, each occurred twice in the molecule, once in the d- and once in the l-configuration. The biosynthetic origin of pagoamide A (1) was considered in light of other natural products investigations with coenocytic green algae.
- Cottrell, Garrison W.,Fang, Fang,Gerwick, Lena,Gerwick, William H.,Glukhov, Evgenia,Guan, Huashi,Kim, Hyunwoo,Leao, Tiago,Li, Yueying,Mao, Huanru Henry,Murray, Thomas F.,Pierce, Marsha L.,Yu, Hao-Bing,Zhang, Chen,Zhang, Yi
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supporting information
(2020/01/31)
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- Structure-guided engineering of: Pseudomonas dacunhae l-aspartate β-decarboxylase for l-homophenylalanine synthesis
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Structure-guided engineering of Pseudomonas dacunhael-aspartate β-decarboxylase (AspBDC) resulted in a double mutant (R37A/T382G) with remarkable 15400-fold improvement in specific activity reaching 216 mU mg-1, towards the target substrate 3(R)-benzyl-l-aspartate. A novel strategy for enzymatic synthesis of l-homophenylalanine was developed by using the variant as a biocatalyst affording 75% product yield within 12 h. Our results underscore the potential of engineered AspBDC for the biocatalytic synthesis of pharmaceutically relevant and value added unnatural l-amino acids.
- Zhang, Min,Hu, Pengfei,Zheng, Yu-Cong,Zeng, Bu-Bing,Chen, Qi,Zhang, Zhi-Jun,Xu, Jian-He
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p. 13876 - 13879
(2020/11/18)
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- Krisynomycins, Imipenem Potentiators against Methicillin-Resistant Staphylococcus aureus, Produced by Streptomyces canus
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A reinvestigation of the acetone extract of the strain CA-091830 of Streptomyces canus, producer of the imipenem potentiator krisynomycin, resulted in the isolation of two additional analogues, krisynomycins B (1) and C (2), with different chlorination patterns. Genome sequencing of the strain followed by detailed bioinformatics analysis led to the identification of the corresponding biosynthetic gene cluster (BGC) of this cyclic nonribosomal peptide family. The planar structure of the new molecules was determined using HRMS, ESI-qTOF-MS/MS, and 1D and 2D NMR data. Their absolute configuration was proposed using a combination of Marfey's and bioinformatic BGC analyses. The krisynomycins displayed weak to negligible antibiotic activity against methicillin-resistant Staphylococcus aureus (MRSA), which was significantly enhanced when tested in combination with sublethal concentrations of imipenem. The halogenation pattern plays a key role in the antimicrobial activity and imipenem-potentiating effects of the compounds, with molecules having a higher number of chlorine atoms potentiating the effect of imipenem at lower doses.
- De La Cruz, Mercedes,Genilloud, Olga,González, Ignacio,Martín, Jesús,Oves-Costales, Daniel,Pérez-Bonilla, Mercedes,Reyes, Fernando,Vicente, Francisca
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p. 2597 - 2606
(2020/10/12)
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- Stalobacin: Discovery of Novel Lipopeptide Antibiotics with Potent Antibacterial Activity against Multidrug-Resistant Bacteria
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A novel lipopeptide antibiotic, stalobacin I (1), was discovered from a culture broth of an unidentified Gram-negative bacterium. Stalobacin I (1) had a unique chemical architecture composed of an upper and a lower half peptide sequence, which were linked via a hemiaminal methylene moiety. The sequence of 1 contained an unusual amino acid, carnosadine, 3,4-dihydroxyariginine, 3-hydroxyisoleucine, and 3-hydroxyaspartic acid, and a novel cyclopropyl fatty acid. The antibacterial activity of 1 against a broad range of drug-resistant Gram-positive bacteria was much stronger than those of last resort antibiotics such as vancomycin, linezolid, and telavancin (MIC 0.004-0.016 μg/mL). Furthermore, compound 1 induced a characteristic morphological change in Gram-positive and Gram-negative strains by inflating the bacterial cell body. The absolute configuration of a cyclopropyl amino acid, carnosadine, was determined by the synthetic study of its stereoisomers, which was an essential component for the strong activity of 1.
- Matsui, Kouhei,Matsui, Kouhei,Kan, Yukiko,Kikuchi, Junko,Matsushima, Keisuke,Takemura, Miki,Maki, Hideki,Kozono, Iori,Ueda, Taichi,Minagawa, Kazuyuki
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supporting information
p. 6090 - 6095
(2020/07/10)
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- Dynamic Kinetic Resolution for Asymmetric Synthesis of L-Noncanonical Amino Acids from D-Ser Using Tryptophan Synthase and Alanine Racemase
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L-Ser is often used to synthesize some significant l-noncanonical α-amino acids(l-ncAAs), which are the prevalent intermediates and precursors for functional synthetic compounds. In this study, threonine aldolase from Escherichia coli k-12 MG1655 has been used to synthesize l-Ser. In contrast to the maximum catalytic capacity (20 g/L) for l-threonine aldolase(LTA), d-Ser was synthesized with high yield (240 g/L) from cheap Gly and paraformaldehyde using d-threonine aldolase (DTA) from Arthrobacter sp ATCC. In order to fully utilize d-Ser and expand the resource of l-Ser, a dynamic kinetic resolution system was constructed to convert d/dl-Ser to l-Ser through combining alanine racemase (Alr) from Bacillus subtilis with l-tryptophan synthase (TrpS) from Escherichia coli k-12 MG1655, and l-ncAAs including l-Trp and l-Cys derivatives were synthesized with excellent enantioselectivity and in high yields. The results indicated l-ncAAs could be efficiently synthesized from d-Ser using this original and green dynamic kinetic resolution system, and the reliable l-Ser resource has been established from simple and achiral substrates.
- Yu, Jinhai,Li, Jing,Gao, Xia,Zeng, Shuiyun,Zhang, Hongjuan,Liu, Junzhong,Jiao, Qingcai
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p. 6618 - 6625
(2019/11/03)
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- Natural Hydroxamate-Containing Siderophore Acremonpeptides A-D and an Aluminum Complex of Acremonpeptide D from the Marine-Derived Acremonium persicinum SCSIO 115
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Four new hydroxamate-containing natural product cyclopeptides designated acremonpeptides A-D (1-4), together with Al(III)-acremonpeptide D (5) were obtained from the marine fungus Acremonium persicinum SCSIO 115. The planar structures of 1-5 were established on the basis of HRMS as well as 1D and 2D NMR data sets. Moreover, the amino acid absolute configurations were determined using Marfey's method. Compounds 1-5 all feature three 2-amino-5-(N-hydroxyacetamido)pentanoic acid (N5-hydroxy-N5-acetyl-l-ornithine) metal ion chelating moieties. Beyond their discovery and structure elucidation, in vitro bioassays revealed acremonpeptides A (1), B (2), and Al(III)-acremonpeptide D (5) as moderate antiviral agents for herpes simplex virus 1 with EC50 values of 16, 8.7, and 14 μM, respectively.
- Chen, Ziming,Huang, Hongbo,Ju, Jianhua,Luo, Minghe,Song, Xiaoxian,Wang, Xin,Zang, Ruochen
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p. 2594 - 2600
(2019/10/11)
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- Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce
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Pseudomonas cichorii, which causes varnish spots on lettuce and seriously damages lettuce production during the summer season in the highland areas of Japan (e.g., Nagano and Iwate prefectures) was isolated. The structure of a toxin produced by this organism was analyzed based on the detailed evaluation of its 2D NMR and FABMS spectra, and this compound has not been reported previously. We propose the name cichorinotoxin for this toxin. In conjunction with the D or L configurations of each amino acid, which were determined by Marfey’s method, we propose the structure of cichorinotoxin to be as follows: 3-hydroxydecanoyl-(Z)-dhThr1-D-Pro2-D-Ala3-D-Ala4-D-Ala5-D-Val6-D-Ala7-(Z)-dhThr8-Ala9-Val10-D-Ile11-Ser12-Ala13-Val14-Ala15-Val16-(Z)-dhThr17-D-alloThr18-Ala19-L-Dab20-Ser21-Val22, and an ester linkage is present between D-alloThr18 and Val22 (dhThr: 2-aminobut-2-enoic acid; Dab: 2,4-diaminobutanoic acid). Thus, the toxin is a lipodepsipeptide with 22 amino acids. The mono- and tetraacetate derivatives and two alkaline hydrolysates, compounds A and B, were prepared. We discuss here the structure–activity relationships between the derivatives and their necrotic activities toward lettuce.
- Komatsu, Hidekazu,Shirakawa, Takashi,Uchiyama, Takeo,Hoshino, Tsutomu
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p. 299 - 309
(2019/02/20)
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- Library Selection with a Randomized Repertoire of (βα)8-Barrel Enzymes Results in Unexpected Induction of Gene Expression
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The potential of the frequently encountered (βα)8-barrel fold to acquire new functions was tested by an approach combining random mutagenesis and selection in vivo. For this purpose, the genes encoding 52 different phosphate-binding (βα)8-barrel proteins were subjected to error-prone PCR and cloned into an expression plasmid. The resulting mixed repertoire was used to transform different auxotrophic Escherichia coli strains, each lacking an enzyme with a phosphate-containing substrate. After plating of the different transformants on minimal medium, growth was observed only for two strains, lacking either the gene for the serine phosphatase SerB or the phosphoserine aminotransferase SerC. The same mutants of the E. coli genes nanE (encoding a putative N-acetylmannosamine-6-phosphate 2-epimerase) and pdxJ (encoding the pyridoxine 5′-phosphate synthase) were responsible for rescuing both ΔserB and ΔserC. Unexpectedly, the complementing NanE and PdxJ variants did not catalyze the SerB or SerC reactions in vitro. Instead, RT-qPCR, RNAseq, and transcriptome analysis showed that they rescue the deletions by enlisting the help of endogenous E. coli enzymes HisB and HisC through exclusive up-regulation of histidine operon transcription. While the promiscuous SerB activity of HisB is well-established, our data indicate that HisC is promiscuous for the SerC reaction, as well. The successful rescue of ΔserB and ΔserC through point mutations and recruitment of additional amino acids in NanE and PdxJ provides another example for the adaptability of the (βα)8-barrel fold.
- Rohweder, Bettina,Lehmann, Gerhard,Eichner, Norbert,Polen, Tino,Rajendran, Chitra,Ruperti, Fabian,Linde, Mona,Treiber, Thomas,Jung, Oona,Dettmer, Katja,Meister, Gunter,Bott, Michael,Gronwald, Wolfram,Sterner, Reinhard
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p. 4207 - 4217
(2019/10/17)
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- Preparation and characterization of a new open-tubular capillary column for enantioseparation by capillary electrochromatography
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In order to use the enantioseparation capability of cationic cyclodextrin and to combine the advantages of capillary electrochromatography (CEC) with open-tubular (OT) column, in this study, a new OT-CEC, coated with cationic cyclodextrin (1-allylimidazolium-β-cyclodextrin [AI-β-CD]) as chiral stationary phase (CSP), was prepared and applied for enantioseparation. Synthesized AI-β-CD was characterized by infrared (IR) spectrometry and mass spectrometry (MS). The preparation conditions for the AI-β-CD-coated column were optimized with the orthogonal experiment design L9(34). The column prepared was characterized by scanning electron microscopy (SEM) and elemental analysis (EA). The results showed that the thickness of stationary phase in the inner surface of the AI-β-CD-coated columns was about 0.2 to 0.5?μm. The AI-β-CD content in stationary phase based on the EA was approximately 2.77?mmol·m?2. The AI-β-CD-coated columns could separate all 14 chiral compounds (histidine, lysine, arginine, glutamate, aspartic acid, cysteine, serine, valine, isoleucine, phenylalanine, salbutamol, atenolol, ibuprofen, and napropamide) successfully in the study and exhibit excellent reproducibility and stability. We propose that the column, coated with AI-β-CD, has a great potential for enantioseparation in OT-CEC.
- Li, Yingjie,Tang, Yimin,Qin, Shili,Li, Xue,Dai, Qiang,Gao, Lidi
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p. 283 - 292
(2019/02/05)
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- Using the 3-Diethylaminobenzyl Group as a Photocage in Aqueous Solution
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We have demonstrated that the 3-diethylaminobenzyl (DEABn) photolabile protecting group (PPG) is an effective and structurally simple PPG for releasing molecules in aqueous environment. In general, the photoreaction is clean, and the released substrate and the PPG product, i.e., 3-diethylaminobenzyl alcohol, are obtained in high yield. The clean photoreaction can also be achieved under mild ambient conditions with sunlight, while the reactant is stable under indoor lighting. Release of two substrates from one PPG chromophore in aqueous solution has been demonstrated to be feasible. We have also compared the uncaging properties of the DEABn and the widely used o-nitrobenzyl (o-NB) group, given their comparable structural simplicity. With its clean and efficient photochemical reaction, DEABn should find wide applications, including in the basic and applied research areas where o-NB and its various derivatives are widely used.
- Ding, Xiong,Wang, Pengfei
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p. 7459 - 7466
(2018/05/29)
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- Colony-wise Analysis of a Theonella swinhoei Marine Sponge with a Yellow Interior Permitted the Isolation of Theonellamide i
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There are several examples of marine organisms whose metabolic profiles differ among conspecifics inhabiting the same region. We have analyzed the metabolic profile of each colony of a Theonella swinhoei marine sponge with a yellow interior and noticed the patchy distribution of one metabolite. This compound was isolated and its structure was studied by a combination of spectrometric analyses and chemical degradation, showing it to be a congener in the theonellamide class of bicyclic peptides. Theonellamides had previously been isolated by us only from T. swinhoei with a white interior and not from those with a yellow interior.
- Fukuhara, Kazuya,Takada, Kentaro,Watanabe, Ryuichi,Suzuki, Toshiyuki,Okada, Shigeru,Matsunaga, Shigeki
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p. 2595 - 2599
(2018/12/13)
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- One-Pot Preparation of d-Amino Acids Through Biocatalytic Deracemization Using Alanine Dehydrogenase and Ω-Transaminase
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d-Amino acids are pharmaceutically important building blocks, leading to a great deal of research efforts to develop cost-effective synthetic methods. Preparation of d-amino acids by deracemization has been conceptually attractive owing to facile synthesis of racemic amino acids by Strecker synthesis. Here, we demonstrated biocatalytic deracemization of aliphatic amino acids into d-enantiomers by running cascade reactions; (1) stereoinversion of l-amino acid to a d-form by amino acid dehydrogenase and ω-transaminase and (2) regeneration of NAD+ by NADH oxidase. Under the cascade reaction conditions containing 100?mM isopropylamine and 1?mM NAD+, complete deracemization of 100?mM dl-alanine was achieved after 24?h with 95% reaction yield of d-alanine (> 99% eeD, 52% isolation yield). Graphical Abstract: [Figure not available: see fulltext.].
- Han, Sang-Woo,Shin, Jong-Shik
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p. 3678 - 3684
(2018/10/20)
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- Sustainable and Continuous Synthesis of Enantiopure l-Amino Acids by Using a Versatile Immobilised Multienzyme System
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The enzymatic synthesis of α-amino acids is a sustainable and efficient alternative to chemical processes, through which achieving enantiopure products is difficult. To more address this synthesis efficiently, a hierarchical architecture that irreversibly co-immobilises an amino acid dehydrogenase with polyethyleneimine on porous agarose beads has been designed and fabricated. The cationic polymer acts as an irreversible anchoring layer for the formate dehydrogenase. In this architecture, the two enzymes and polymer colocalise across the whole microstructure of the porous carrier. This multifunctional heterogeneous biocatalyst was kinetically characterised and applied to the enantioselective synthesis of a variety of canonical and noncanonical α-amino acids in both discontinuous (batch) and continuous modes. The co-immobilised bienzymatic system conserves more than 50 % of its initial effectiveness after five batch cycles and 8 days of continuous operation. Additionally, the environmental impact of this process has been semiquantitatively calculated and compared with the state of the art.
- Velasco-Lozano, Susana,da Silva, Eunice S.,Llop, Jordi,López-Gallego, Fernando
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p. 395 - 403
(2017/11/13)
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- Complex-precipitation using functionalized chiral ionic liquids with L-proline anion and chromatographic analysis for enantioseparation of racemic amino acids
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As one kind of functionalized green medium, chiral ionic liquids (CILs) have been widely applied in fields of asymmetric catalysis, enantioseparation, and so on. In this study, four kinds of amino acid–based CILs were synthesized by using trimethylamine, N-methylpyrrolidine, N-methylimidazole, and tropine as cationic nucleus, respectively. Then their specific optical rotation and solubility in common solvents were determined for further resolution application. The effect of different cations in these CILs was explored on the separation of racemic phenylalanine in complex-precipitation way. Moreover, various factors were systematically investigated for their effects on resolution efficiency, including the type of additive copper salts, the molar ratio of Cu (II) to CIL, pH value, the amount of racemic phenylalanine, and temperature. Under the appropriate conditions, L-phenylalanine mainly existed in solid phase and could be separated from its enantiomers in liquid phase. Furthermore, the mechanism of resolution was studied by thermogravimetric analysis, infrared spectrum, and molecular simulation. The resolution system has characteristics of no organic solvent, fast separation speed, simple resolution process, and easy scale-up.
- Zang, Huimin,Yao, Shun,Luo, Yingjie,Tang, Dan,Song, Hang
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p. 1182 - 1194
(2018/09/12)
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- Purification, structural characterization and bioactivity evaluation of a novel proteoglycan produced by Corbicula fluminea
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A novel proteoglycan, named CFPS-11, was isolated from Corbicula fluminea, which is a food source of freshwater bivalve mollusk. CFPS-11 had an average molecular weight of 807.7 kDa and consisted of D-glucose and D-glucosamine in a molar ratio of 12.2:1.0. The protein moiety (~5%) of CFPS-11 was covalently bonded to the polysaccharide chain in O-linkage type through both serine and thereonine residues. The polysaccharide chain of CFPS-11 was composed of (1 → 4)-α-D-glucopyranosyl and (1 → 3,6)-α-D-glucopyranosyl residues, which branched at O-6. The branch chain consisted of (1 →)-α-D-glucopyranosyl and (1 →)-α-D-N-acetylglucosamine residues. CFPS-11 exhibited significant antioxidant activity in a dose-dependent manner and remarkable inhibition activities against α-amylase and α-glucosidase by in vitro assays. These findings indicated that the CFPS-11 from C. fluminea has the potential for development as a health food ingredient.
- Yan, Jing-Kun,Wang, Yao-Yao,Qiu, Wen-Yi,Wu, Li-Xia,Ding, Zhi-Chao,Cai, Wu-Dan
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- Chromatographic Resolution of α-Amino Acids by (R)-(3,3'-Halogen Substituted-1,1'-binaphthyl)-20-crown-6 Stationary Phase in HPLC
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Three new chiral stationary phases (CSPs) for high-performance liquid chromatography were prepared from R-(3,3'-halogen substituted-1,1'-binaphthyl)-20-crown-6 (halogen = Cl, Br and I). The experimental results showed that R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6 (CSP-1) possesses more prominent enantioselectivity than the two other halogen-substituted crown ether derivatives. All twenty-one α-amino acids have different degrees of separation on R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6-based CSP-1 at room temperature. The enantioselectivity of CSP-1 is also better than those of some commercial R-(1,1'-binaphthyl)-20-crown-6 derivatives. Both the separation factors (α) and the resolution (Rs) are better than those of commercial crown ether-based CSPs [CROWNPAK CR(+) from Daicel] under the same conditions for asparagine, threonine, proline, arginine, serine, histidine and valine, which cannot be separated by commercial CR(+). This study proves the commercial usefulness of the R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6 chiral stationary phase.
- Wu, Peng,Wu, Yuping,Zhang, Junhui,Lu, Zhenyu,Zhang, Mei,Chen, Xuexian,Yuan, Liming
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supporting information
p. 1037 - 1042
(2017/07/25)
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- Efficient Enzymatic Preparation of13N-Labelled Amino Acids: Towards Multipurpose Synthetic Systems
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Nitrogen-13 can be efficiently produced in biomedical cyclotrons in different chemical forms, and its stable isotopes are present in the majority of biologically active molecules. Hence, it may constitute a convenient alternative to Fluorine-18 and Carbon-11 for the preparation of positron-emitter-labelled radiotracers; however, its short half-life demands for the development of simple, fast, and efficient synthetic processes. Herein, we report the one-pot, enzymatic and non-carrier-added synthesis of the13N-labelled amino acids l-[13N]alanine, [13N]glycine, and l-[13N]serine by using l-alanine dehydrogenase from Bacillus subtilis, an enzyme that catalyses the reductive amination of α-keto acids by using nicotinamide adenine dinucleotide (NADH) as the redox cofactor and ammonia as the amine source. The integration of both l-alanine dehydrogenase and formate dehydrogenase from Candida boidinii in the same reaction vessel to facilitate the in situ regeneration of NADH during the radiochemical synthesis of the amino acids allowed a 50-fold decrease in the concentration of the cofactor without compromising reaction yields. After optimization of the experimental conditions, radiochemical yields were sufficient to carry out in vivo imaging studies in small rodents.
- da Silva, Eunice S.,Gómez-Vallejo, Vanessa,Baz, Zuri?e,Llop, Jordi,López-Gallego, Fernando
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p. 13619 - 13626
(2016/09/13)
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- Influence of the amino acid side chain on peptide bond hydrolysis catalyzed by a dimeric Zr(iv)-substituted Keggin type polyoxometalate
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Peptide bond hydrolysis of 18 different dipeptides, divided into four groups depending on the nature of the amino acid side chain, by the dimeric Zr(iv)-substituted Keggin type polyoxometalate (POM) (Et2NH2)8[{α-PW11O39Zr-(μ-OH)(H2O)}2]·7H2O (1) was studied by means of kinetic experiments and 1H/13C NMR spectroscopy. The observed rate constants highly depend on the bulkiness and chemical nature of the X amino acid side chain. X-Ser and X-Thr dipeptides showed increased reactivity due to intramolecular nucleophilic attack of the hydroxyl group in the side chain on the amide carbon, resulting in a reactive ester intermediate. A similar effect in which the amino acid side chain acted as an internal nucleophile was observed for the hydrolysis of Gly-Asp. Interestingly, in the presence of 1 deamidation of Gly-Asn and Gly-Gln into Gly-Asp and Gly-Glu was observed. Dipeptides containing positively charged amino acid side chains were hydrolyzed at higher rates due to electrostatic interactions between the negatively charged POM surface and positive amino acid side chains.
- Ly, Hong Giang T.,Absillis, Gregory,Parac-Vogt, Tatjana N.
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supporting information
p. 976 - 984
(2016/02/19)
-
- Cyclopentapeptides from Dianthus chinensis
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A new cyclopentapeptide dianthin I (1), together with two known ones pseudostellarin A (2) and heterophyllin J (3), was isolated from the aerial parts of Dianthus chinensis. The structure of 1 was elucidated as cyclo-(Gly1- l-Phe2- l-Pro3- l-Ser4- l-Phe5) on the basis of extensive spectroscopic analyses and chemical methods.
- Han, Jing,Huang, Maobo,Wang, Zhe,Zheng, Yuqing,Zeng, Guangzhi,He, Wenjun,Tan, Ninghua
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p. 550 - 553
(2015/07/02)
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- Enantiospecific C-H Activation Using Ruthenium Nanocatalysts
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The activation of C-H bonds has revolutionized modern synthetic chemistry. However, no general strategy for enantiospecific C-H activation has been developed to date. We herein report an enantiospecific C-H activation reaction followed by deuterium incorporation at stereogenic centers. Mechanistic studies suggest that the selectivity for the α-position of the directing heteroatom results from a four-membered dimetallacycle as the key intermediate. This work paves the way to novel molecular chemistry on nanoparticles.
- Taglang, Céline,Martínez-Prieto, Luis Miguel,Del Rosal, Iker,Maron, Laurent,Poteau, Romuald,Philippot, Karine,Chaudret, Bruno,Perato, Serge,Sam Lone, Ana?s,Puente, Céline,Dugave, Christophe,Rousseau, Bernard,Pieters, Grégory
-
supporting information
p. 10474 - 10477
(2015/09/02)
-
- Site-specific labeling of synthetic peptide using the chemoselective reaction between N-methoxyamino acid and isothiocyanate
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Site-specific labeling of synthetic peptides carrying N-methoxyglycine (MeOGly) by isothiocyanate is demonstrated. A nonapeptide having MeOGly at its N-terminus was synthesized by the solid-phase method and reacted with phenylisothiocyanate under various conditions. In acidic solution, the reaction specifically gave a peptide having phenylthiourea structure at its N-terminus, leaving side chain amino group intact. The synthetic human β-defensin-2 carrying MeOGly at its N-terminus or the side chain amino group of Lys10 reacted with phenylisothiocyanate or fluorescein isothiocyanate also at the N-methoxyamino group under the same conditions, demonstrating that this method is generally useful for the site-specific labeling of linear synthetic peptides as well as disulfide-containing peptides.
- Hara, Toshiaki,Purwati, Euis Maras,Tainosyo, Akira,Kawakami, Toru,Hojo, Hironobu,Aimoto, Saburo
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p. 765 - 769
(2015/09/21)
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- Isolation, Characterization, and Synthesis of the Barrettides: Disulfide-Containing Peptides from the Marine Sponge Geodia barretti
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Two disulfide-containing peptides, barrettides A (1) and B (2), from the cold-water marine sponge Geodia barretti are described. Those 31 amino acid residue long peptides were sequenced using mass spectrometry methods and structurally characterized using NMR spectroscopy. The structure of 1 was confirmed by total synthesis using the solid-phase peptide synthesis approach that was developed. The two peptides were found to differ only at a single position in their sequence. The three-dimensional structure of 1 revealed that these peptides possess a unique fold consisting of a long β-hairpin structure that is cross-braced by two disulfide bonds in a ladder-like arrangement. The peptides are amphipathic in nature with the hydrophobic and charged residues clustered on separate faces of the molecule. The barrettides were found not to inhibit the growth of either Escherichia coli or Staphylococcus aureus but displayed antifouling activity against barnacle larvae (Balanus improvisus) without lethal effects in the concentrations tested. (Figure Presented).
- Carstens, Bodil B.,Rosengren, K. Johan,Gunasekera, Sunithi,Schempp, Stefanie,Bohlin, Lars,Dahlstr?m, Mia,Clark, Richard J.,G?ransson, Ulf
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p. 1886 - 1893
(2015/09/08)
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- Microseiramide from the freshwater cyanobacterium Microseira sp. UIC 10445
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Abstract Microseiramide (1), a cyclic heptapeptide, was isolated from a sample of the freshwater cyanobacterium Microseira sp. UIC 10445 collected in a shallow lake in Northern Indiana. Taxonomic identification of UIC 10445 was performed by a combination of morphological and phylogenetic characterization. Phylogenetic analysis revealed that UIC 10445 was a member of the recently described genus Microseira, which is phylogenetically distinct from the morphologically similar genera, Moorea and Lyngbya. The planar structure of microseiramide (1) was determined by extensive 1D and 2D NMR experiments as well as HRESIMS analysis. The absolute configurations of amino acid residues were determined using acid hydrolysis followed by the advanced Marfey's analysis. Microseiramide (1) is the first cyclic peptide reported from a Microseira sp., and the structure of microseiramide (1) is distinct from the previously known metabolites from cyanobacteria of the genera Moorea and Lyngbya.
- Luo, Shangwen,Krunic, Aleksej,Chlipala, George E.,Orjala, Jimmy
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- Comparative study of the reactivity of zirconium(IV)-substituted polyoxometalates towards the hydrolysis of oligopeptides
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The hydrolytic activity of the ZrIV-substituted Keggin-type (Et2NH2)8[{α-PW11O39Zr-(μ-OH)(H2O)}2]·7H2O (1), Lindqvist-type (Me4N)2[W5O18Zr(H2O)3] (2), and Wells-Dawson-type Na14[Zr4(P2W16O59)2(μ3-O)2(OH)2(H2O)4]·57H2O (3) polyoxometalates (POMs) towards the peptide bonds in the oligopeptides triglycine, tetraglycine, glycylglycylhistidine, and glycylserylphenylalanine was investigated by kinetic methods and multinuclear NMR spectroscopy. 31P NMR and UV/Vis spectroscopy showed that 1-3 were stable under the conditions used to study peptide bond hydrolysis. The reactivity of 1-3 towards oligopeptides was compared on the basis of the amount of free glycine produced at a certain time increment. In the presence of 1-3, rate constants in the range 6.25×10-7 to 10.14×10-7 s-1 were obtained, whereas no hydrolysis was observed after one month in the absence of these POMs. The results showed that the Keggin-type complex 1 was the most active towards peptide bond hydrolysis in tri- and tetrapeptides. 1H and 13C NMR spectroscopy showed that triglycine, tetraglycine, and glycylserylphenylalanine interact with 1 and 2 preferentially through the amine nitrogen atom and the N-terminal amide oxygen atom to activate the peptide bond towards hydrolysis. The coordination of glycylglycylhistidine resulted in multiple complexes with 1-3 as a result of additional imidazole coordination to the ZrIV centers.
- Ly, Hong Giang T.,Absillis, Gregory,Parac-Vogt, Tatjana N.
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p. 2206 - 2215
(2015/05/13)
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- Characterization of two putative prolinases (PepR1 and PepR2) from Lactobacillus plantarum WCFS1: Occurrence of two isozymes with structural similarity and different catalytic properties
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Two putative prolinases (PepR1 and PepR2) of Lactobacillus plantarum WCSF1 share 48.5% amino acid sequence identity (55.5% at the DNA level); however, PepR1 exhibits over 80% identity at the protein level with other lactobacilli prolinases while PepR2 exhibits only 51% or less identity. In this study, the putative genes were overexpressed in Escherichia coli, purified to gel electrophoretic homogeneity, and then characterized. Purified PepR1 and PepR2 hydrolysed Pro-Xaa dipeptide substrates at similar rates, proving their nature as prolinases. Structural analyses using circular dichroism, dynamic light scattering, gel filtration, and molecular modelling revealed that the two prolinases have similar structural characteristics: high β-sheet content, homotetrameric structure, and similar folding to the PepI/PepL/PepR peptidase family. However, kinetic and thermodynamic analyses of PepR1 and PepR2 indicated differences in many aspects: optimum temperatures (25 and 30 °C, respectively), optimum pH (pH 7.5 and 8.0, respectively), substrate specificities (high stringency of PepR2), kinetic parameters, and thermal stability (29 and 48 °C, respectively). Also, these prolinases behaved differently towards inhibitor treatments, suggesting structural and/or functional differences in their active sites. Differences in the two prolinases would contribute to a diversity of catalytic activities, so that they work together cooperatively and complementarily to hydrolyse proline-containing peptides with broader specificity, working pH, working temperature, and higher efficiency, thus allowing adaptation to a wider range of environments.
- Huang, Yanyu,Tanaka, Takuji
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- Degradation and antioxidant activities of peptides and zinc-peptide complexes during in vitro gastrointestinal digestion
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The degradation characteristics of three peptides (Ser-Met, Asn-Cys-Ser, and glutathione) and their zinc-peptide complexes were studied using a two-stage in vitro digestion model. Enzyme-resistant peptides and zinc-peptide complexes, antioxidant activities, and free amino acids released by digestive enzymes, were measured in this study. The results revealed that the three peptides and their zinc-peptide complexes were resistant to pepsin but not to pancreatin. Pancreatin can partly hydrolyse both peptides and zinc-peptide complexes, but more than half of them remaining in their original form after gastrointestinal digestion. The coordination of zinc improved the enzymatic resistance of the peptide due to lower solubility of complexes and affected the hydrolytic site of pepsin and pancreatin. Zinc-Asn-Cys-Ser, which is highly resistant to enzymatic hydrolysis and maintains Zn in a soluble form, may have potential to improve Zn bioavailability.
- Wang, Chan,Li, Bo,Wang, Bo,Xie, Ningning
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p. 733 - 740
(2015/01/09)
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- Characterization of a novel amine transaminase from Halomonas elongata
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Chiral amines are indispensable building blocks in the production of biologically active compounds. They are fundamental for the pharmaceutical industry, both as active molecules themselves and as chiral auxiliaries in asymmetric synthesis; however, the available synthetic strategies often present disadvantages. ω-Transaminases (ω-TAs) appear as an attractive alternative by driving the stereoselective amination of prochiral ketones. HEWT is a novel amine transaminase from the moderate halophilic bacterium, Halomonas elongata DSM 2581, which is highly (S)-selective, being able to fully convert (S)-1-phenylethylamine to acetophenone and showing no activity with the corresponding (R)-1-phenylethylamine. HEWT has a broad substrate scope, active with a range of amino donors and acceptors, and naturally accepts isopropylamine (IPA) as amino donor in asymmetric synthesis providing a 41% conversion of pyruvate in 24 h at 37°C starting with 1:1 molar ratio between the reagents. HEWT also accepts ortho-xylylenediamine as amino donor in for amine synthesis, in particular, with benzaldehyde yielding high conversions between 90 and 95%. The enzyme is also tolerant to the presence of cosolvents up to 20% making it a promising candidate for industrial applications.
- Cerioli, Lorenzo,Planchestainer, Matteo,Cassidy, Jennifer,Tessaro, Davide,Paradisi, Francesca
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p. 141 - 150
(2015/09/01)
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- Structures and solution conformational dynamics of stylissamides G and H from the Bahamian Sponge Stylissa caribica
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Two new peptides, stylissamides G and H, were isolated from extracts of a sample of Stylissa caribica collected in deep waters of the Caribbean Sea. A single sample of S. caribica among a collection of 10 samples that were examined by LC-MS appeared to be a different chemotype from the others in that it lacked the familiar pyrrole-2-aminoimidazole alkaloids, stevensine and oroidin, and contained peptides of the stylissamide class. The structures of the title compounds were solved by integrated analysis of the MS and NMR spectra and chemical degradation. The solution conformation of stylissamide G was briefly examined by electronic circular dichroism and temperature-dependent 1H NMR chemical shifts of amide NH signals, which supported a conformationally rigid macrocycle.
- Wang, Xiao,Morinaka, Brandon I.,Molinski, Tadeusz F.
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supporting information
p. 625 - 630
(2014/04/17)
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- A novel serine hydroxymethyltransferase from marine bacterium Alcanivorax sp. and its application on enzymatic synthesis of L-serine
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A novel glyA gene from the marine bacterium Alcanivorax sp. was cloned and expressed in Escherichia coli BL21 (DE3). The recombinant glyA encodes a polypeptide of 418 amino acids, which was designated as AdSHMT that shows the highest identity (70%) with a SHMT from Shewanella algae. The purified enzyme showed a single band at about 45 kDa by SDS-PAGE analysis. It was found that AdSHMT exhibited the maximal activity at 50 °C and pH 7.0. The K m, Vmax, and Kcat values of AdSHMT against dl-threo-3-phenylserine were calculated to be 0.097 mol/L, 3.255 μmol/min/mg and 2.451/s, respectively. More importantly, RP-HPLC detection showed that the AdSHMT achieved an 88.37% molecular conversion rate in catalyzing glycine to l-serine, with the final concentration of l-serine being 353.15 mM in the reaction at 35°C and 22nd hour when the initial concentration of the substrate (glycine) was 0.399 M. The molecular conversion rate of the AdSHMT from the Alcanivorax sp. was 1.26-fold that of the EcSHMT from the E. coli, which is currently applied in industrial production. Therefore, AdSHMT has the potential for industrial applications due to its high enzymatic conversion rate.
- Yuan, Shaohui,Jiang, Wei,Chen, Lin,Guo, Yiming,Liu, Ziduo
-
-
- Modification of cellulose acetates for preparing chiral sorbents
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Modification of cellulose acetates via sorption-desorption of vapors of mesogenic solvents in which the polymer forms a lyotropic liquid crystal phase and of mixtures of these solvents with water leads to the formation of a new chiral structure of the polymeric sample. This is manifested in a significant change in the value and even sign of the specific optical rotation of the polysaccharide system. The sorbents based on cellulose acetates that have been modified by such treatment exhibit specific affinity for definite optical antipodes. When a racemic mixture of L- and D-isomers of amino acids is passed through this sorbent, it acts as a chiral filter owing to "steric recognition" of one of the enantiomers, so that the filtrate contains an optically pure product (isomer). The revealed effects served as a basis for the development of a new procedure for preparation of optically pure stereoisomers of chiral products.
- Shipovskaya,Gegel',Shchegolev
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p. 1326 - 1333
(2015/05/20)
-
- Chemical evolution of simple amino acids to asparagine under discharge onto the primitive hydrosphere: Simulation experiments using contact glow discharge
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Asparagine is an important amino acid for abiotic polypeptide synthesis. In simulation experiments, it was obtained in 3.0% yield (based on the amount of consumed alanine) from alanine (100 mM) and formamide (200 mM) by contact glow discharge (Harada discharge) onto aqueous solutions. The present results suggest that asparagine could be abiotically synthesized from simple amino acids under possible primitive earth conditions.
- Munegumi, Toratane
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p. 1208 - 1215
(2015/02/19)
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- Deracemization of amino acids by coupling transaminases of opposite stereoselectivity
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Biocatalytic deracemization of amino acids without relying on oxidase-based deamination of an unwanted enantiomer was demonstrated by coupling a-and w-transaminases displaying opposite stereoselectivity. This strategy employs isopropylamine and a keto acid as cosubstrates and is free of generation of hydrogen peroxide which is troublesome in the conventional oxidase-based methods.
- Park, Eul-Soo,Shin, Jong-Shik
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p. 3505 - 3509
(2015/02/19)
-
- A novel serine hydroxymethyltransferase from marine bacterium Alcanivorax sp. and its application on enzymatic synthesis of L-serine
-
A novel glyA gene from the marine bacterium Alcanivorax sp. was cloned and expressed in Escherichia coli BL21 (DE3). The recombinant glyA encodes a polypeptide of 418 amino acids, which was designated as AdSHMT that shows the highest identity (70%) with a SHMT from Shewanella algae. The purified enzyme showed a single band at about 45 kDa by SDS-PAGE analysis. It was found that AdSHMT exhibited the maximal activity at 50 °C and pH 7.0. The Km, Vmax, and Kcatvalues of AdSHMT against dl-threo-3-phenylserine were calculated to be 0.097 mol/L, 3.255 μmol/min/mg and 2.451/s, respectively. More importantly, RP-HPLC detection showed that the AdSHMT achieved an 88.37% molecular conversion rate in catalyzing glycine to l-serine, with the final concentration of l-serine being 353.15 mM in the reaction at 35 °C and 22nd hour when the initial concentration of the substrate (glycine) was 0.399 M. The molecular conversion rate of the AdSHMT from the Alcanivorax sp. was 1.26-fold that of the EcSHMT from the E. coli, which is currently applied in industrial production. Therefore, AdSHMT has the potential for industrial applications due to its high enzymatic conversion rate.
- Yuan, Shaohui,Jiang, Wei,Chen, Lin,Guo, Yiming,Liu, Ziduo
-
-
- Probing of primed and unprimed sites of calpains: Design, synthesis and evaluation of epoxysuccinyl-peptide derivatives as selective inhibitors
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Calpains are intracellular cysteine proteases with important physiological functions. Up- or downregulation of their expression can be responsible for several diseases, therefore specific calpain inhibitors may be considered as promising candidates for drug discovery. In this paper we describe the synthesis and characterization of a new class of inhibitors derived from the analysis of amino acid preferences in primed and unprimed sites of calpains by incorporation of l- or d-epoxysuccinyl group (Eps). Amino acids for replacement were chosen by considering the substrate preference of calpain 1 and 2 enzymes. The compounds were characterized by RP-HPLC, amino acid analysis and ESI-MS. Selectivity of the compounds was studied by using calpain 1 and 2; and cathepsin B. We have identified five calpain specific inhibitors with different extent of selectivity. Two of these also exhibited isoform selectivity. Compound NH 2-Thr-Pro-Leu-(d-Eps)-Thr-Pro-Pro-Pro-Ser-NH2 proved to be a calpain 2 enzyme inhibitor with at least 11.8-fold selectivity, while compound NH2-Thr-Pro-Leu-(l-Eps)-Ser-Pro-Pro-Pro-Ser-NH2 possesses calpain 1 enzyme inhibition with at least 4-fold selectivity. The results of molecular modeling calculations suggest that the orientation of the bound inhibitor in the substrate binding cleft is markedly dependent on the stereochemistry of the epoxysuccinyl group.
- Dókus, Levente E.,Menyhárd, Dóra K.,Tantos, ágnes,Hudecz, Ferenc,Bánóczi, Zoltán
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supporting information
p. 274 - 280
(2014/06/24)
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- Biochemical characterisation and assessment of fibril-forming ability of collagens extracted from Bester sturgeon Huso huso × Acipenser ruthenus
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Collagens purified from Bester sturgeon organs were characterised biochemically, and their fibril-forming abilities and fibril morphologies formed in vitro clarified. Yields of collagens were 2.1%, 11.9%, 0.4%, 18.1%, 0.4%, 0.8% and 0.03% (collagen dry weight/tissue wet weight) from scales, skin, muscle, swim bladder, digestive tract, notochord and snout cartilage, respectively. Using SDS-PAGE and amino acid composition analyses, collagens from scales, skin, muscle, the swim bladder and digestive tract were characterised as type I, and collagens from the notochord and snout cartilage as type II. Denaturation temperatures of the collagens, measured using circular dichroism, were 29.6, 26.8, 29.0, 32.9, 31.6 and 36.3 °C in scales, skin, muscle, swim bladder, digestive tract, and notochord, respectively. For fibril formation, swim bladder and skin collagen showed a more rapid rate of increase in turbidity, a shorter time to attain the maximum turbidity, and formed thicker fibrils compared with porcine tendon type I collagen.
- Zhang, Xi,Ookawa, Mika,Tan, Yongkai,Ura, Kazuhiro,Adachi, Shinji,Takagi, Yasuaki
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p. 305 - 312
(2014/05/06)
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- SEPARATING AGENT AND MANUFACTURING METHOD THEREOF
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An embodiment of the present invention is a separating agent wherein a group represented by a chemical formula of: or a group represented by a chemical formula of: is introduced on a surface thereof.
- -
-
Paragraph 0067; 0068; 0069; 0070; 0071; 0072; 0091; 0092
(2015/01/07)
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- Astins K-P, six new chlorinated cyclopentapeptides from Aster tataricus
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During further investigation on the methanol extract of roots and rhizomes of Aster tataricus, six new chlorinated cyclopentapeptides, designated as astins K-P (9-14), together with eight known derivatives, astins A-H (1-8), were isolated. Structures of the new cyclopeptides were established using extensive spectroscopic methods, and the absolute configurations were determined by the advanced Marfey's method. Astin P (14) represents a unique cyclopentapeptide linking as cyclo-(l-Pro (Cl2)1-l-allo-Thr 2-l-Ser3-l-β-Phe4-l-Ava5). Astin B (2) showed cytotoxicity against BGC-823 cell with IC50 value of 19.2 μg/ml. Astin C (3) exhibited cytotoxicity on HCT-116 and BGC-823 cells with IC50 values of 13.4 and 3.3 μg/ml, respectively.
- Xu, Hui-Min,Zeng, Guang-Zhi,Zhou, Wen-Bing,He, Wen-Jun,Tan, Ning-Hua
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p. 7964 - 7969
(2013/08/23)
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- HR-MALDI-MS imaging assisted screening of β-Carboline alkaloids discovered from mycena metata
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Fruiting bodies of Mycena metata were screened for the presence of new secondary metabolites by means of HPLC-UV, LC-HR-ESIMS, and high-resolution matrix-assisted laser desorption/ionization mass spectrometry imaging (HRMALDI- MS imaging). Thus, a new β-carboline alkaloid, 6-hydroxymetatacarboline D (1d), was isolated from fruiting bodies of M. metata. 6-Hydroxymetatacarboline D consists of a highly substituted β-carboline skeleton, which is likely to be derived biosynthetically from L-tryptophan, 2-oxoglutaric acid, L-threonine, and L-proline. The structure of the alkaloid was established by 2D NMR spectroscopic methods and HR-ESIMS. Moreover, by extensive application of LC-HR-ESIMS, LC-HR-ESIMS/MS, and LC-HR-ESIMS3 techniques we were able to elucidate the structures of a number of accompanying β-carboline alkaloids, 1a- 1c, 1e-1i, and 2a-2g, structurally closely related to 6-hydroxymetatacarboline D, which are present in M. metata in minor amounts. The absolute configuration of the stereogenic centers of the β-carboline alkaloids was determined by GC-MS comparison with authentic synthetic samples after hydrolytic cleavage and derivatization of the resulting amino acids.
- Jaeger, Robert J. R.,Lamshoeft, Marc,Gottfried, Sebastian,Spiteller, Michael,Spiteller, Peter
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p. 127 - 134
(2013/06/27)
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- ω-Transaminase-catalyzed asymmetric synthesis of unnatural amino acids using isopropylamine as an amino donor
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Isopropylamine is an ideal amino donor for reductive amination of carbonyl compounds by ω-transaminase (ω-TA) owing to its cheapness and high volatility of a ketone product. Here we developed asymmetric synthesis of unnatural amino acids via ω-TA-catalyzed amino group transfer between α-keto acids and isopropylamine.
- Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
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p. 6929 - 6933
(2013/10/08)
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- Using the 9-BBN group as a transient protective group for the functionalization of reactive chains of α-amino acids
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Achieving chemoselectivity is a longstanding challenge in chemical synthesis. This problem has been addressed using different approaches, but a definitive solution is still pending. For instance, in peptide chemistry, particularly with amino acids containing side chains functionalities with reactivity patterns similar to the main functional groups, such as aspartic and glutamic acids, and lysine and ornithine, specific semi-permanent protecting groups have been employed. The use of 9-borabicyclo[3.3.1]nonane (9-BBN-H) as a transient protective group for the selective protection of α-amino acids, which allows the chemoselective manipulation of the functional groups embedded in the side chains of the molecule, is described.
- Sanchez, Adrian,Calderon, Ernesto,Vazquez, Alfredo
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p. 1364 - 1372
(2013/07/05)
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- In situ deprotection and incorporation of unnatural amino acids during cell-free protein synthesis
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The S30 extract from E. coli BL21 Star (DE3) used for cell-free protein synthesis removes a wide range of α-amino acid protecting groups by cleaving α-carboxyl hydrazides; methyl, benzyl, tert-butyl, and adamantyl esters; tert-butyl and adamantyl carboxamides; α-amino form-, acet-, trifluoroacet-, and benzamides and sidechain hydrazides and esters. The free amino acids are produced and incorporated into a protein under standard conditions. This approach allows the deprotection of amino acids to be carried out in situ to avoid separate processing steps. The advantages of this approach are demonstrated by the efficient incorporation of the chemically intractable (S)-4-fluoroleucine, (S)-4,5- dehydroleucine, and (2S,3R)-4-chlorovaline into a protein through the direct use of their respective precursors, namely, (S)-4-fluoroleucine hydrazide, (S)-4,5-dehydroleucine hydrazide, and (2S,3R)-4-chlorovaline methyl ester. These results also show that the fluoroand dehydroleucine and the chlorovaline are incorporated into a protein by the normal biosynthetic machinery as substitutes for leucine and isoleucine, respectively. Copyright
- Arthur, Isaac N.,Hennessy, James E.,Padmakshan, Dharshana,Stigers, Dannon J.,Lesturgez, Stéphanie,Fraser, Samuel A.,Liutkus, Mantas,Otting, Gottfried,Oakeshott, John G.,Easton, Christopher J.
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p. 6824 - 6830
(2013/06/26)
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- Six new cyclic peptides from the roots of gypsophila oldhamiana
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Six new cyclic peptides, gypsophin A-F (1-6), were isolated from Gypsophila oldhamiana. Their structures were elucidated by extensive NMR and chemical degradation. Compound 3 exhibited moderate activity of antiplatelet aggregation in vitro.
- Wang, Gang,Luo, Jian-Guang,Yang, Ming-Hua,Wang, Xiao-Bing,Kong, Ling-Yi
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p. 489 - 495
(2013/06/05)
-
- SEPARATING AGENT FOR CHROMATOGRAPHY
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A separating agent for chromatography is provided that is useful for the separation of specific compounds, e.g., for the optical resolution of amino acids. This separating agent for chromatography provides a higher productivity and contains a crown ether-like cyclic structure and optically active binaphthyl. This separating agent for chromatography containing a crown ether-like cyclic structure and optically active binaphthyl is provided by introducing a substitution group for binding to carrier into a specific commercially available 1,1′-binaphthyl derivative that has substituents at the 2, 2′, 3, and 3′ positions, then introducing a crown ether-like cyclic structure, and subsequently chemically bonding the binaphthyl derivative to the carrier through the substitution group for binding to carrier.
- -
-
Paragraph 0074; 0075
(2013/08/15)
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- Amino acid side chain induced selectivity in the hydrolysis of peptides catalyzed by a Zr(iv)-substituted Wells-Dawson type polyoxometalate
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In this paper the reactivity of K15H[Zr(α2- P2W17O61)2]·25H2O (1), a Zr(iv)-substituted Wells-Dawson polyoxometalate, is examined towards a series of Gly-Aa, Aa-Gly or Aa-Ser dipeptides, in which the nature and the size of the Aa amino acid side chain were varied. The rate of peptide bond hydrolysis, determined by 1H NMR experiments, in Gly-Aa dipeptides is strongly dependent on the molecular volume and the chemical structure of the Aa side chain. When the volume of the aliphatic side chain of the Aa residue in Gly-Aa increased, a clear decrease in the hydrolysis rate was observed. Replacing one α-H in the C-terminal Gly residue of Gly-Gly by a methyl group (Gly-Ala) resulted in a 6-fold reactivity decrease, pointing towards the importance of steric factors for efficient peptide bond hydrolysis. The rate constants for peptide bond hydrolysis in Gly-Aa dipeptides at pD 5.0 and 60 °C ranged from 208.0 ± 15.6 × 10-6 min-1 for Gly-Ser to 5.0 ± 1.0 × 10-6 min-1 for Gly-Glu, reflecting the influence of the different nature of the amino acid side chains on the hydrolysis rate. Faster hydrolysis was observed for peptides containing Ser and Thr since the hydroxyl group in their side chain is able to facilitate amide bond hydrolysis by promoting an N→O acyl rearrangement. Peptides containing positively charged side chains at pD 5.0 show enhanced hydrolysis rates as a result of the secondary electrostatic interactions with the negatively charged surface of the polyoxometalate, which stabilize the peptide-polyoxometalate complex. A slow hydrolysis rate was observed for Gly-Glu, because of the preferential coordination of the carboxylate group in the side chain of Glu to Zr(iv), which prevents coordination of the peptide carbonyl group and its activation towards hydrolysis.
- Vanhaecht, Stef,Absillis, Gregory,Parac-Vogt, Tatjana N.
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p. 15437 - 15446
(2013/11/06)
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