- Role of conserved histidine residues in D-aminoacylase from Alcaligenes xylosoxydans subsp. xylosoxydans A-6
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D-Aminoacylase from Alcaligenes xylosoxydans subsp. xylosoxydans A-6 (Alcaligenes A-6) was strongly inactivated by diethylpyrocarbonate (DEPC). An H67N mutant was barely active, with a kcat/Km 6.3 × 104 times lower than that of the recombinant wild-type enzyme, while the H67I mutant lost detectable activity. The H67N mutant had almost constant Km, but greatly decreased kcat. These results suggested that His67 is essential to the catalytic event. Both H69N and H69I mutants were overproduced in the insoluble fraction. The kcat/Km of H250N mutant was reduced by a factor of 2.5 × 104-old as compared with the wild-type enzyme. No significant difference between H251N mutant and wild-type enzymes in the Km and kcat was found. The Zn content of H250N mutant was nearly half of that of wild-type enzyme. These results suggest that the His250 residue might be essential to catalysis via Zn binding.
- Wakayama, Mamoru,Yada, Harutaka,Kanda, Shun-Ichi,Hayashi, Shin-Ichi,Yatsuda, Yukinori,Sakai, Kenji,Moriguchi, Mitsuaki
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Read Online
- Structures and antitumor activities of ten new and twenty known surfactins from the deep-sea bacterium Limimaricola sp. SCSIO 53532
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Surfactins are natural biosurfactants with myriad potential applications in the areas of healthcare and environment. However, surfactins were almost exclusively produced by the bacterium Bacillus species in previous reported literatures, together with difficulty in isolating pure monomer, which resulted in making extensive effort to remove duplication and little discovery of new surfactins in recent years. In the present study, the result of Molecular Networking indicated that Limimaricola sp. SCSIO 53532 might well be a potential resource for surfacin-like compounds based on OSMAC strategy. To search for new surfactins with significant biological activity, further study was undertaken on the strain. As a result, ten new surfactins (1–10), along with twenty known surfactins (11–30), were isolated from the ethyl acetate extract of SCSIO 53532. Their chemical structures were established by detailed 1D and 2D NMR spectroscopy, HRESIMS data, secondary ion mass spectrometry (MS/MS) analysis, and chemical degradation (Marfey's method) analysis. Cytotoxic activities of twenty-seven compounds against five human tumor cell lines were tested, and five compounds showed significant antitumor activities with IC50 values less than 10 μM. Furtherly, analysis of structure–activity relationships revealed that the branch of side chain, the esterification of Glu or Asp residue, and the amino acid residue of position 7 possessed a great influence on antitumor activity.
- Chen, Min,Chen, Rouwen,Ding, Wenping,Li, Yanqun,Tian, Xinpeng,Yin, Hao,Zhang, Si
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- Adiponectin-Secretion-Promoting Cyclic Peptide-Polyketide Hybrids from a Halophyte-Associated Fungus, Colletotrichum gloeosporioides JS0417
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Three new cyclic peptide-polyketide hybrids (1-3) and two new chaetiacandin-type polyketides (4 and 5) along with nine known compounds were isolated from cultures of a halophyte-associated fungus, Colletotrichum gloeosporioides JS0417. Spectroscopic analysis revealed that 1-3 were cyclic depsipeptides where 3,5,11-trihydroxy-2,6-dimethyldodecanoic acid was linked to two amino acids through amide and ester bonds to form a 12-membered ring. Relative and absolute configurations for the peptides were determined with spectroscopic analysis and chemical reactions. The cyclic depsipeptides 2 and 6 were determined to act as strong adiponectin-secretion-promoting modulators with potential to treat metabolic diseases associated with hypoadiponectinemia. Notably, a known compound, tryptophol, significantly inhibited PGE2synthesis and also promoted adiponectin secretion, exhibiting a similar biological activity profile to aspirin, but with greater potency. The presence of an isoleucine moiety and non-glycosylation may be important for biological activity of the cyclic peptide-polyketide hybrids, and non-methoxylation of the side chain may influence activity of the indole derivatives.
- An, Seungchan,Bang, Sunghee,Deyrup, Stephen T.,Gong, Junpyo,Kim, Jaekyeong,Ko, Hyejin,Lee, Changyeol,Noh, Minsoo,Shim, Sang Hee
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- Structures and Biosynthetic Pathway of Coprisamides C and D, 2-Alkenylcinnamic Acid-Containing Peptides from the Gut Bacterium of the Carrion Beetle Silpha perforata
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Coprisamides C and D (1 and 2) were isolated from a gut bacterium, Micromonospora sp. UTJ3, of the carrion beetle Silpha perforata. Based on the combined analysis of UV, MS, and NMR spectral data, the planar structures of 1 and 2 were elucidated to be unreported derivatives of coprisamides A and B, cyclic depsipeptides bearing a 2-alkenylcinnamic acid unit and the unusual amino acids β-methylaspartic acid and 2,3-diaminopropanoic acid. The absolute configuration of 1 was determined using the advanced Marfey's method, phenylglycine methyl ester derivatization, and J-based configuration analysis. The biosynthetic gene clusters for the coprisamides were investigated based on genomic data from coprisamide-producing strains Micromonospora sp. UTJ3 and Streptomyces sp. SNU533. Coprisamide C (1) was active against the Mycobacterium tuberculosis mc26230 strain.
- Shin, Yern-Hyerk,Ban, Yeon Hee,Kim, Tae Ho,Bae, Eun Seo,Shin, Jongheon,Lee, Sang Kook,Jang, Jichan,Yoon, Yeo Joon,Oh, Dong-Chan
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- Single-step fluorescent probes to detect decrotonylation activity of HDACs through intramolecular reactions
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Lysine crotonylation plays vital roles in gene transcription and cellular metabolism. Nevertheless, methods for dissecting the molecular mechanisms of decrotonyaltion remains limited. So far, there is no single-step fluorescent method developed for enzymatic decrotonylation activity detection. The major difficulty is that the aliphatic crotonylated lysine doesn't allow π-conjugation to a fluorophore and decrotonylation can not modulate the electronic state directly. Herein, we have designed and synthesized two activity-based single-step fluorogenic probes KTcr-I and KTcr-II for detecting enzymatic decrotonylation activity. These two probes can be recognized by histone deacetylases and undergo intramolecular nucleophilic exchange reaction to generate fluorescence signal. Notably, peptide sequence-dependent effect was observed. KTcr-I can be recognized by Sirt2 more effectively, while KTcr-II with LGKcr peptide sequence preferentially reacted with HDAC3. Compared to other methods of studying enzymatic decrotonylation activity, our single-step fluorescent method has a number of advantages, such as facileness, high sensitivity, cheap facility and little material consumed. We envision that the probes developed in this study will provide useful tools to screen inhibitors which suppress the decrotonylation activity of HDACs. Such probes will be useful for further delineating the roles of decrotonylation enzyme and aid in biomarker identification and drug discovery.
- Xie, Yusheng,Yang, Liu,Chen, Qingxin,Zhang, Jie,Feng, Ling,Chen, Jian Lin,Hao, Quan,Zhang, Liang,Sun, Hongyan
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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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- Exploration of Transaminase Diversity for the Oxidative Conversion of Natural Amino Acids into 2-Ketoacids and High-Value Chemicals
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The use of 2-ketoacids is very common in feeds, food additives, and pharmaceuticals, and 2-ketoacids are valuable precursors for a plethora of chemically diverse compounds. Biocatalytic synthesis of 2-ketoacids starting from l-amino acids would be highly desirable because the substrates are readily available from biomass feedstock. Here, we report bioinformatic exploration of a series of aminotransferases (ATs) to achieve the desired conversion. Thermodynamic control was achieved by coupling an l-glutamate oxidation reaction in the cascade for the recycling of the amine acceptor. These enzymes were able to convert a majority of proteinogenic amino acids into the corresponding 2-ketoacids with high conversion (up to 99percent) and atom-efficiency. Furthermore, this enzyme cascade was extendable, and one-pot two-step processes were established for the synthesis of d-amino acids and N-methylated amino acids, achieving great overall conversion (up to 99percent) and high ee values (>99percent). These developed enzymatic methodologies offer convenient routes for utilizing amino acids as synthetic reagents.
- Chen, Yanchun,Cui, Xuexian,Cui, Yinglu,Li, Chuijian,Li, Ruifeng,Li, Tao,Sun, Jinyuan,Wu, Bian,Zhu, Tong
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p. 7950 - 7957
(2020/08/21)
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- Highly selective synthesis of d-amino acids from readily available l-amino acids by a one-pot biocatalytic stereoinversion cascade
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d-Amino acids are key intermediates required for the synthesis of important pharmaceuticals. However, establishing a universal enzymatic method for the general synthesis of d-amino acids from cheap and readily available precursors with few by-products is challenging. In this study, we constructed and optimized a cascade enzymatic route involving l-amino acid deaminase and d-amino acid dehydrogenase for the biocatalytic stereoinversions of l-amino acids into d-amino acids. Using l-phenylalanine (l-Phe) as a model substrate, this artificial biocatalytic cascade stereoinversion route first deaminates l-Phe to phenylpyruvic acid (PPA) through catalysis involving recombinant Escherichia coli cells that express l-amino acid deaminase from Proteus mirabilis (PmLAAD), followed by stereoselective reductive amination with recombinant meso-diaminopimelate dehydrogenase from Symbiobacterium thermophilum (StDAPDH) to produce d-phenylalanine (d-Phe). By incorporating a formate dehydrogenase-based NADPH-recycling system, d-Phe was obtained in quantitative yield with an enantiomeric excess greater than 99%. In addition, the cascade reaction system was also used to stereoinvert a variety of aromatic and aliphatic l-amino acids to the corresponding d-amino acids by combining the PmLAAD whole-cell biocatalyst with the StDAPDH variant. Hence, this method represents a concise and efficient route for the asymmetric synthesis of d-amino acids from the corresponding l-amino acids.
- Zhang, Danping,Jing, Xiaoran,Zhang, Wenli,Nie, Yao,Xu, Yan
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p. 29927 - 29935
(2019/10/01)
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- Chemical and Metagenomic Studies of the Lethal Black Band Disease of Corals Reveal Two Broadly Distributed, Redox-Sensitive Mixed Polyketide/Peptide Macrocycles
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Black band disease (BBD), a lethal, polymicrobial disease consortium dominated by the cyanobacterium Roseofilum reptotaenium, kills many species of corals worldwide. To uncover chemical signals or cytotoxins that could be important in proliferation of Roseofilum and the BBD layer, we examined the secondary metabolites present in geographically diverse collections of BBD from Caribbean and Pacific coral reefs. Looekeyolide A (1), a 20-membered macrocyclic compound formed by a 16-carbon polyketide chain, 2-deamino-2-hydroxymethionine, and d-leucine, and its autoxidation product looekeyolide B (2) were extracted as major compounds (~1 mg g-1 dry wt) from more than a dozen field-collected BBD samples. Looekeyolides A and B were also produced by a nonaxenic R. reptotaenium culture under laboratory conditions at similar concentrations. R. reptotaenium genomes that were constructed from four different metagenomic data sets contained a unique nonribosomal peptide/polyketide biosynthetic cluster that is likely responsible for the biosynthesis of the looekeyolides. Looekeyolide A, which readily oxidizes to looekeyolide B, may play a biological role in reducing H2O2 and other reactive oxygen species that could occur in the BBD layer as it overgrows and destroys coral tissue.
- Gunasekera, Sarath P.,Meyer, Julie L.,Ding, Yousong,Abboud, Khalil A.,Luo, Danmeng,Campbell, Justin E.,Angerhofer, Alexander,Goodsell, Justin L.,Raymundo, Laurie J.,Liu, Junyang,Ye, Tao,Luesch, Hendrik,Teplitski, Max,Paul, Valerie J.
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p. 111 - 121
(2019/01/21)
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- Artificial Biocatalytic Cascade with Three Enzymes in One Pot for Asymmetric Synthesis of Chiral Unnatural Amino Acids
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Two biocatalytic reactions, transamination catalyzed by transaminases and reductive amination catalyzed by amino acid dehydrogenases, can be used for asymmetric synthesis of optically pure unnatural amino acids. However, although transaminases show a great diversity and broad substrate spectrum, most transaminase reactions are reversible, while amino acid dehydrogenases catalyze reductive amination irreversibly but with strict substrate specificity. Accordingly, herein we developed a tri-enzyme one-pot reaction system to exploit the respective advantages of transaminases and amino acid dehydrogenases, while overcoming the disadvantages of each. In this work, representatives of all four subgroups of transaminases coupled with different amino acid dehydrogenases to produce five l- and four d- unnatural amino acid products, using ammonia and the co-enzyme NAD(P)H, which is regenerated by a robust alcohol dehydrogenase with 2-propanol as cheap cosubstrate. The complete conversion and high enantiopurity (ee > 99 %) of the products, demonstrated it as an ideal alternative for asymmetric synthesis of chiral amino acid compounds.
- Zhou, Haisheng,Meng, Lijun,Yin, Xinjian,Liu, Yayun,Xu, Gang,Wu, Jianping,Wu, Mianbin,Yang, Lirong
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supporting information
p. 6470 - 6477
(2019/11/02)
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- Covalent Organic Frameworks with Chirality Enriched by Biomolecules for Efficient Chiral Separation
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The separation of racemic compounds is important in many fields, such as pharmacology and biology. Taking advantage of the intrinsically strong chiral environment and specific interactions featured by biomolecules, here we contribute a general strategy is developed to enrich chirality into covalent organic frameworks (COFs) by covalently immobilizing a series of biomolecules (amino acids, peptides, enzymes) into achiral COFs. Inheriting the strong chirality and specific interactions from the immobilized biomolecules, the afforded biomolecules?COFs serve as versatile and highly efficient chiral stationary phases towards various racemates in both normal and reverse phase of high-performance liquid chromatography (HPLC). The different interactions between enzyme secondary structure and racemates were revealed by surface-enhanced Raman scattering studies, accounting for the observed chiral separation capacity of enzymes?COFs.
- Zhang, Sainan,Zheng, Yunlong,An, Hongde,Aguila, Briana,Yang, Cheng-Xiong,Dong, Yueyue,Xie, Wei,Cheng, Peng,Zhang, Zhenjie,Chen, Yao,Ma, Shengqian
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supporting information
p. 16754 - 16759
(2018/11/27)
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- Discovery of new A- and B-type laxaphycins with synergistic anticancer activity
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Two new cyclic lipopeptides termed laxaphycins B4 (1) and A2 (2) were discovered from a collection of the marine cyanobacterium Hormothamnion enteromorphoides, along with the known compound laxaphycin A. The planar structures were solved based on a combined interpretation of 1D and 2D NMR data and mass spectral data. The absolute configurations of the subunits were determined by chiral LC-MS analysis of the hydrolysates, advanced Marfey's analysis and 1D and 2D ROESY experiments. Consistent with similar findings on other laxaphycin A- and B-type peptides, laxaphycin B4 (1) showed antiproliferative effects against human colon cancer HCT116 cells with IC50 of 1.7 μM, while laxaphycins A and A2 (2) exhibited weak activities. The two major compounds isolated from the sample, laxaphycins A and B4, were shown to act synergistically to inhibit the growth of HCT116 colorectal cancer cells.
- Cai, Weijing,Matthew, Susan,Chen, Qi-Yin,Paul, Valerie J.,Luesch, Hendrik
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p. 2310 - 2319
(2018/04/02)
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- Structure-guided engineering of: Meso -diaminopimelate dehydrogenase for enantioselective reductive amination of sterically bulky 2-keto acids
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meso-Diaminopimelate dehydrogenase (DAPDH) and mutant enzymes are an excellent choice of biocatalysts for the conversion of 2-keto acids to the corresponding d-amino acids. However, their application in the enantioselective reductive amination of bulky 2-keto acids, such as phenylglyoxylic acid, 2-oxo-4-phenylbutyric acid, and indole-3-pyruvic acid, is still challenging. In this study, the structure-guided site-saturation mutagenesis of a Symbiobacterium thermophilum DAPDH (StDAPDH) gave rise to a double-site mutant W121L/H227I, which showed dramatically improved enzyme activities towards various 2-keto acids including these sterically bulky substrates. Several d-amino acids were prepared in optically pure form. The molecular docking of substrates into the active sites of wild-type and mutant W121L/H227I enzymes revealed that the substrate binding cavity of the mutant enzyme was reshaped to accommodate these bulky substrates, thus leading to higher enzyme activity. These results lay a foundation for further shaping the substrate binding pocket and manipulating the interactions between the substrate and binding sites to access highly active d-amino acid dehydrogenases for the preparation of synthetically challenging d-amino acids.
- Cheng, Xinkuan,Chen, Xi,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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p. 4994 - 5002
(2018/10/17)
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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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- Deracemization and Stereoinversion of α-Amino Acids by l-Amino Acid Deaminase
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Enantiomerically pure α-amino acids are compounds of primary interest for the fine chemical, pharmaceutical, and agrochemical sectors. Amino acid oxidases are used for resolving d,l-amino acids in biocatalysis. We recently demonstrated that l-amino acid deaminase from Proteus myxofaciens (PmaLAAD) shows peculiar features for biotechnological applications, such as a high production level as soluble protein in Escherichia coli and a stable binding with the flavin cofactor. Since l-amino acid deaminases are membrane-bound enzymes, previous applications were mainly based on the use of cell-based methods. Now, taking advantage of the broad substrate specificity of PmaLAAD, a number of natural and synthetic l-amino acids were fully converted by the purified enzyme into the corresponding α-keto acids: the fastest conversion was obtained for 4-nitrophenylalanine. Analogously, starting from racemic solutions, the full resolution (ee >99%) was also achieved. Notably, d,l-1-naphthylalanine was resolved either into the d- or the l-enantiomer by using PmaLAAD or the d-amino acid oxidase variant having a glycine at position 213, respectively, and was fully deracemized when the two enzymes were used jointly. Moreover, the complete stereoinversion of l-4-nitrophenylalanine was achieved using PmaLAAD and a small molar excess of borane tert-butylamine complex. Taken together, recombinant PmaLAAD represents an l-specific amino acid deaminase suitable for producing the pure enantiomers of several natural and synthetic amino acids or the corresponding keto acids, compounds of biotechnological or pharmaceutical relevance. (Figure presented.).
- Rosini, Elena,Melis, Roberta,Molla, Gianluca,Tessaro, Davide,Pollegioni, Loredano
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p. 3773 - 3781
(2017/11/13)
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- Octaminomycins A and B, cyclic octadepsipeptides active against Plasmodium falciparum
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Two new cyclic octadepsipeptides, octaminomycins A (1) and B (2), were isolated from a microbial metabolite fraction library of Streptomyces sp. RK85-270 based on Natural Products Plot screening. Their structures were elucidated on the basis of HRESIMS, 1D and 2D NMR spectroscopic data, and MS/MS experiments for sequence analysis. The absolute configurations of the constituent amino acid residues were determined by a combination of single-crystal X-ray diffraction and Marfey's methodology. Notably, octaminomycins A (1) and B (2) showed good in vitro antiplasmodial activity against chloroquine-sensitive as well as chloroquine-resistant strains with no cytotoxicity up to 30 μM. (Chemical Equation Presented).
- Jang, Jun-Pil,Nogawa, Toshihiko,Futamura, Yushi,Shimizu, Takeshi,Hashizume, Daisuke,Takahashi, Shunji,Jang, Jae-Hyuk,Ahn, Jong Seog,Osada, Hiroyuki
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p. 134 - 140
(2017/02/05)
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- Nodupetide, a potent insecticide and antimicrobial from Nodulisporium sp. associated with Riptortus pedestris
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Nodupetide (1), a new cyclodepsipeptide unique in its incorporation of a 3-hydroxy-4-methylhexanoic acid (HMHA) derived motif, was discovered from Nodulisporium sp. IFB-A163, a fungus residing in the insect (Riptortus pedestris) gut. The nodupetide structure was elucidated by its MS/MS and 2D NMR spectra, and its absolute configuration by the X-ray crystallography and modified Marfey's method. Nodupetide is insecticidal against rice brown planthopper (Nilaparvata lugens) with an LD50value of 70?ng/larva, and inhibitory towards the drug-resistant human pathogenic bacterium Pseudomonas aeruginosa with its MIC value (5.0?μM) comparable to that (3.2?μM) of ciprofloxacin, a prescribed antibacterial agent co-assayed equally.
- Wu, Hui Min,Lin, Li Ping,Xu, Qin Lan,Han, Wen Bo,Zhang, Song,Liu, Ze Wen,Mei, Ya Ning,Yao, Zhu Jun,Tan, Ren Xiang
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supporting information
p. 663 - 665
(2017/01/25)
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- A new type of chiral-pyridoxamines for catalytic asymmetric transamination of α-keto acids
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A new type of chiral pyridoxamines bearing an adjacent chiral stereocenter has been developed via multi-step synthesis. The pyridoxamines displayed catalytic activity in asymmetric transamination of α-keto acids to give a variety of optically active amino acids in 27–78% yields with 34–62% ee's under very mild conditions. This work provides a synthetic strategy to construct new chiral pyridoxamines using bromopyridine 7 as a key synthon and also represents an early example of the applications of chiral pyridoxamines in asymmetric catalysis.
- Chen, Jianfeng,Zhao, Junyu,Gong, Xing,Xu, Dongfang,Zhao, Baoguo
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supporting information
p. 4612 - 4615
(2016/09/23)
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- Asymmetric Transamination of α-Keto Acids Catalyzed by Chiral Pyridoxamines
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A new type of novel chiral pyridoxamines 3a-g containing a side chain has been developed. The pyridoxamines displayed catalytic activity and promising enantioselectivity in biomimetic asymmetric transamination of α-keto acids, to give various α-amino acids in 47-90% yields with up to 87% ee's under very mild conditions. An interesting effect of the side chain on enantioselectivity was observed in the reaction.
- Lan, Xiaoyu,Tao, Chuangan,Liu, Xuliang,Zhang, Aina,Zhao, Baoguo
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supporting information
p. 3658 - 3661
(2016/08/16)
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- Novel chiral open-chain pyridoxamine catalyst and synthesis method and application thereof
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The invention relates to a novel chiral open-chain pyridoxamine catalyst and a synthesis method and application thereof. The structural general formula of the pyridoxamine catalyst is shown in the specification, wherein R1, R2, R3 and R4 are one of hydrogen, C1-24 alkyl, C1-24 alkyl containing substituent groups, substances shown in the specification and halogen, the substituent groups on C1-24 alkyl are a substance shown in the specification or a substance shown in the specification or a substance shown in the specification or O-Rw or S-Rw' or halogen, and Rx, Rx', Ry, Ry', Ry'', Rz, Rz', Rw and Rw' are one of hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, tertiary butyl, cyclopentyl, cyclohexyl, cycloheptyl, phenyl, benzyl, (1-phenyl)ethyl, 1-naphthyl, 2-naphthyl and halogen. Compared with the prior art, the pyridoxamine catalyst can achieve rapid and efficient synthesis of chiral amino acid, the preparation raw materials are easy to obtain, reaction conditions are mild, cost is low, and when the novel chiral open-chain pyridoxamine catalyst is used for a transamination reaction, the conditions are mild, and the reaction is stable.
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Paragraph 0175; 0176; 0177; 0178; 0205; 0206; 0207; 0208
(2017/01/19)
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- t-BUTYLKETONE BINAPHTHOL DERIVATIVES AND PREPARING METHOD THEREOF
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The present disclosure relates to a t-butylketone binaphthol derivative and a method of preparing the same, the t-butylketone binaphthol derivative being a high-efficiency chiral extracting agent which has a very high chiral selectivity enabling to extract an amino acid from an aqueous solution phase to an organic layer and to facilitate its hydrolysis, and enabling a continuous reuse of the organic layer.
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Paragraph 0097
(2017/01/17)
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- An easy 'Filter-and-Separate' method for enantioselective separation and chiral sensing of substrates using a biomimetic homochiral polymer
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We present a polyfluorene appended with protected l-glutamic acid that exhibited a reversible α-helix/β-sheet-like conformation and helical porous fibrous morphology mimicking the super-structure of proteins. The new homochiral polymer probe enabled efficient heterogeneous enantioselective separation and chiral sensing of a wide variety of substrates from their aqueous racemic mixture using an easy 'Filter-and-Separate' method.
- Senthilkumar,Asha
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supporting information
p. 8931 - 8934
(2015/05/27)
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- Chiral Pyridoxal-Catalyzed Asymmetric Biomimetic Transamination of α-Keto Acids
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A series of chiral pyridoxals 8 and 9 have been developed from commercially available pyridoxine and (S)-α,α-diarylprolinols. The pyridoxals exhibited good catalytic activity in an asymmetric transamination of α-keto acids with 2,2-diphenylglycine (7f) as the amine source to give various α-amino acids in 29-85% yields with 53-80% ee's. The current asymmetric transamination has successfully mimicked a complete biological transamination process characterized by two half-transaminations, a small chiral pyridoxal molecule acting as the catalyst, and enantioselective control.
- Shi, Limin,Tao, Chuangan,Yang, Qin,Liu, Yong Ethan,Chen, Jing,Chen, Jianfeng,Tian, Jiaxin,Liu, Feng,Li, Bo,Du, Yongling,Zhao, Baoguo
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supporting information
p. 5784 - 5787
(2015/12/11)
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- Efficient synthesis of chiral binaphthol aldehyde with phenyl ether linkage for enantioselective extraction of amino acids
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A binaphthol aldehyde with phenyl ether linkage, compound 2, has been synthesized starting from binaphthol-3-carboxylic acid. The axially chiral binaphthol ring was racemized during the synthesis due to high temperatures required in O-phenylation reaction. The enantiomerically pure form of 2 was obtained from the resolution of the diastereomeric imine of 2. Optically pure compound (S)-2 was applied to the enantioselective liquid-liquid extraction of amino acid between CH2Cl2 and aqueous layers.The stereoselectivities, that is, D/L ratio of the amino acid extracted, ranged from 3.57 to 11.1. One carbon was absent in compound (S)-2 compared to the compound (S)-1 with benzyl ether linkage, which differentiated the conformations of their imines formed with amino acids.
- Choi, Misun,Jun, Moo-Jin,Kim, Kwan Mook
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p. 1834 - 1837
(2015/07/15)
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- Seven new and two known lipopeptides as well as five known polyketides: The activated production of silent metabolites in a marine-derived fungus by chemical mutagenesis strategy using diethyl sulphate
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AD-2-1 is an antitumor fungal mutant obtained by diethyl sulfate mutagenesis of a marine-derived Penicillium purpurogenum G59. The G59 strain originally did not produce any metabolites with antitumor activities in MTT assays using K562 cells. Tracing newly produced metabolites under guidance of MTT assay and TLC analysis by direct comparison with control G59 extract, seven new (1-7) and two known (8-9) lipopeptides were isolated together with five known polyketides 10-14 from the extract of mutant AD-2-1. Structures of the seven new compounds including their absolute configurations were determined by spectroscopic and chemical evidences and named as penicimutalides A-G (1-7). Seven known compounds were identified as fellutamide B (8), fellutamide C (9), 1.-O-methylaverantin (10), averantin (11), averufin (12), nidurufin (13), and sterigmatocystin (14). In the MTT assay, 1-14 inhibited several human cancer cell lines to varying extents. All the bioassays and HPLC-photodiode array detector (PDAD)-UV and HPLC-electron spray ionization (ESI)-MS analyses demonstrated that the production of 1-14 in the mutant AD-2-1 was caused by the activated production of silent metabolites in the original G59 fungal strain. Present results provided additional examples for effectiveness of the chemical mutagenesis strategy using diethyl sulphate mutagenesis to discover new compounds by activating silent metabolites in fungal isolates.
- Wu, Chang-Jing,Li, Chang-Wei,Cui, Cheng-Bin
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p. 1815 - 1838
(2014/06/09)
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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.
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Paragraph 0067; 0068; 0069; 0070; 0071; 0072; 0085; 0086
(2015/01/07)
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- New phenethylamine derivatives from Arenibacter nanhaiticus sp. nov. NH36A T and their antimicrobial activity
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Five new phenethylamine (PEA) derivatives (1-5) were isolated from the strain of Arenibacter nanhaiticus sp. nov. NH36A T derived from the marine sediment of the South China Sea by bioassay-guided fractionation. Their structures were elucidated by spectro
- Chen, Yanping,Tang, Jinshan,Tang, Xixiang,Wang, Chuanxi,Lian, Yunyang,Shao, Zongze,Yao, Xinsheng,Gao, Hao
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p. 655 - 661
(2014/01/06)
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- Champacyclin, a new cyclic octapeptide from Streptomyces strain C42 isolated from the Baltic Sea
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New isolates of Streptomyces champavatii were isolated from marine sediments of the Gotland Deep (Baltic Sea), from the Urania Basin (Eastern Mediterranean), and from the Kiel Bight (Baltic Sea). The isolates produced several oligopeptidic secondary metabolites, including the new octapeptide champacyclin (1a) present in all three strains. Herein, we report on the isolation, structure elucidation and determination of the absolute stereochemistry of this isoleucine/leucine (Ile/Leu = Xle) rich cyclic octapeptide champacyclin (1a). As 2D nuclear magnetic resonance (NMR) spectroscopy could not fully resolve the structure of (1a), additional information on sequence and configuration of stereocenters were obtained by a combination of multi stage mass spectrometry (MSn) studies, amino acid analysis, partial hydrolysis and subsequent enantiomer analytics with gas chromatography positive chmical ionization/electron impact mass spectrometry (GC-PCI/EI-MS) supported by comparison to reference dipeptides. Proof of the head-to-tail cyclization of (1a) was accomplished by solid phase peptide synthesis (SPPS) compared to an alternatively side chain cyclized derivative (2). Champacyclin (1a) is likely synthesized by a non-ribosomal peptide synthetase (NRPS), because of high content of (D)-amino acids. The compound (1a) showed antimicrobial activity against the phytopathogen Erwinia amylovora causing the fire blight disease of certain plants.
- Pesic, Alexander,Baumann, Heike I.,Kleinschmidt, Katrin,Ensle, Paul,Wiese, Jutta,Suessmuth, Roderich D.,Imhoff, Johannes F.
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p. 4834 - 4857
(2014/02/14)
-
- Protease inhibitors from microcystis aeruginosa bloom material collected from the dalton reservoir, israel
-
Nine new metabolites, aeruginosins DA495A (1), DA511 (2), DA642A (3), DA642B (4), DA688 (5), DA722 (6), and DA495B (7), microguanidine DA368 (8), and anabaenopeptin DA850 (9), were isolated along with the known micropeptins MZ924, MZ939A, and MZ1019, cyanopeptolins S and SS, microcin SF608, and aeruginazoles DA1497, DA1304, and DA1274 from bloom material of the cyanobacterium Microcystis aeruginosa collected from the Dalton reservoir, Israel, in October 2007. Their structures were elucidated by a combination of various spectroscopic techniques, primarily NMR and MS, while the absolute configurations of the asymmetric centers were determined by Marfey's and chiral-phase HPLC methods. Two of the new aeruginosins, DA511 (1) and DA495A (2), contain a new Choi isomer, (2S,3aS,6S,7aS)-Choi. The structure elucidation and biological activities of the new metabolites are described.
- Adiv, Simi,Carmeli, Shmuel
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p. 2307 - 2315
(2014/01/17)
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- Structure and biosynthesis of xenoamicins from entomopathogenic xenorhabdus
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During the search for novel natural products from entomopathogenic Xenorhabdus doucetiae DSM17909 and X. mauleonii DSM17908 novel peptides named xenoamicins were identified in addition to the already known antibiotics xenocoumacin and xenorhabdin. Xenoamicins are acylated tridecadepsipeptides consisting of mainly hydrophobic amino acids. The main derivative xenoamicin A (1) was isolated from X. mauleonii DSM17908, and its structure elucidated by detailed 1 D and 2 D NMR experiments. Detailed MS experiments, also in combination with labeling experiments, confirmed the determined structure and allowed structure elucidation of additional derivatives. Moreover, the xenoamicin biosynthesis gene cluster was identified and analyzed in X. doucetiae DSM17909, and its participation in xenoamicin biosynthesis was confirmed by mutagenesis. Advanced Marfey's analysis of 1 showed that the absolute configuration of the amino acids is in agreement with the predicted stereochemistry deduced from the nonribosomal peptide synthetase XabABCD. Biological testing revealed activity of 1 against Plasmodium falciparum and other neglected tropical diseases but no antibacterial activity.
- Zhou, Qiuqin,Grundmann, Florian,Kaiser, Marcel,Schiell, Matthias,Gaudriault, Sophie,Batzer, Andreas,Kurz, Michael,Bode, Helge B.
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supporting information
p. 16772 - 16779
(2014/01/06)
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- Surugamides A-E, cyclic octapeptides with four D-amino acid residues, from a marine streptomyces sp.: LC-MS-aided inspection of partial hydrolysates for the distinction of D- and L-amino acid residues in the sequence
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Surugamides A-E (1-5), cyclic octapeptides with four d-amino acid residues, were isolated from the broth of marine-derived Streptomyces sp. Their planar structures were determined by analyses of spectroscopic data, and the absolute configuration of constituent amino acid residues was determined by the Marfey's method. Differentiation of d-Ile and l-Ile in the sequence was established by chiral analysis of fragment peptides obtained from the partial hydrolysate, whose identification was conducted by LC-MS/MS.
- Takada, Kentaro,Ninomiya, Akihiro,Naruse, Masato,Sun, Yi,Miyazaki, Masayuki,Nogi, Yuichi,Okada, Shigeru,Matsunaga, Shigeki
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p. 6746 - 6750
(2013/07/26)
-
- 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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- Biocatalytic asymmetric synthesis of unnatural amino acids through the cascade transfer of amino groups from primary amines onto keto acids
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Flee to the hills: An unfavorable equilibrium in the amino group transfer between amino acids and keto acids catalyzed by α-transaminases was successfully overcome by coupling with a ω-transaminase reaction as an equilibrium shifter, leading to efficient asymmetric synthesis of diverse unnatural amino acids, including L-tert-leucine and D-phenylglycine. Copyright
- Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
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p. 3538 - 3542
(2014/01/06)
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- Isolation, structure elucidation and total synthesis of lajollamide a from the marine fungus Asteromyces cruciatus
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The marine-derived filamentous fungus Asteromyces cruciatus 763, obtained off the coast of La Jolla, San Diego, USA, yielded the new pentapeptide lajollamide A (1), along with the known compounds regiolone (2), hyalodendrin (3), gliovictin (4), 1N-norgliovicitin (5), and bis-N-norgliovictin (6). The planar structure of lajollamide A (1) was determined by Nuclear Magnetic Resonance (NMR) spectroscopy in combination with mass spectrometry. The absolute configuration of lajollamide A (1) was unambiguously solved by total synthesis which provided three additional diastereomers of 1 and also revealed that an unexpected acid-mediated partial racemization (2:1) of the L-leucine and L-N-Me-leucine residues occurred during the chemical degradation process. The biological activities of the isolated metabolites, in particular their antimicrobial properties, were investigated in a series of assay systems.
- Gulder, Tobias A. M.,Hong, Hanna,Correa, Jhonny,Egereva, Ekaterina,Wiese, Jutta,Imhoff, Johannes F.,Gross, Harald
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p. 2912 - 2935
(2013/02/23)
-
- METHOD FOR OBTAINING OPTICALLY PURE AMINO ACIDS
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This invention relates to a method for obtaining optically pure amino acids, including optical resolution and optical conversion. This method significantly shortens the time taken for optical transformation, and enables the repeated use of an organic solution containing a enantioselective receptor, to thereby obtain optically pure amino acids in a simple and remarkably efficient manner, and to enable the very economical mass production of optically pure amino acids.
- -
-
Page/Page column 7
(2012/02/01)
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- METHOD FOR OBTAINING OPTICALLY PURE AMINO ACIDS
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This invention relates to a method for obtaining optically pure amino acids, including optical resolution and optical conversion. This method significantly shortens the time taken for optical transformation, and enables the repeated use of an organic solution containing a enantioselective receptor, to thereby obtain optically pure amino acids in a simple and remarkably efficient manner, and to enable the very economical mass production of optically pure amino acids.
- -
-
Page/Page column 10-11
(2012/02/14)
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- Chiral imprinting with amino acids of ordered mesoporous silica exhibiting enantioselectivity after calcination
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Chiral ordered mesoporous silica (COMS) was synthesized in basic media by combining tetraethyl orthosilicate and quaternized aminosilane (with a templating role) silica sources together with four different standard amino acids (arginine, histidine, isoleucine, and proline). Besides the hexagonal MCM-41-type structure, narrow pore size distribution, and high specific surface area, it was found that these solids have potential for enantiomeric separation because of the transference of chirality from the amino acid to the silica. This is illustrated by the resolution of several racemic mixtures (those of proline, isoleucine, trans-4-hydroxyproline, pipecolic acid, valine, leucine, and phenylglycine) with the calcined COMS prepared with l-proline. The opposite behavior observed in induced circular dichroism experiments with calcined COMS, obtained using both enantiomers of proline, confirmed their chiral nature. The high number and variety of existing amino acids, and chiral organic compounds in general, makes these ordered silicas attractive for the production of enantiopure substances.(Figure Presented)
- Lacasta, Susana,Sebastian, Victor,Casado, Clara,Mayoral, Alvaro,Romero, Pilar,Larrea, Angel,Vispe, Eugenio,Lopez-Ram-De-Viu, Pilar,Uriel, Santiago,Coronas, Joaquin
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scheme or table
p. 1280 - 1287
(2012/02/15)
-
- Isolation and characterization of peptide antibiotics LI-F04 and polymyxin B6 produced by Paenibacillus polymyxa strain JSa-9
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Paenibacillus polymyxa JSa-9 had been found to produce five cyclic LI-F type antibiotics which were released into culture medium in accordance with our previous report. In this study, another three kinds of antagonistic compounds were extracted from P. polymyxa JSa-9 cell pellets and (or) spores by methanol. Using high performance liquid chromatography (HPLC) method, two antagonistic fractions were separated and collected from the methanol extract. One showed inhibition against Escherichia coli and Staphylococcus aureus, while the other was active against Aspergillus niger and S. aureus. By means of electrospray ionization mass spectroscopy (ESI-MS), infrared spectroscopy (IR), and amino acid analysis, two kinds of compounds from fraction B with molecular masses of 901 and 915 Da were characterized as the linear lipopeptide analogs of antibiotics LI-F04a and LI-F04b, respectively. Another antimicrobial substance from fraction A could be attributed to polymyxin B6.
- Deng, Yang,Lu, Zhaoxin,Bi, Hua,Lu, Fengxia,Zhang, Chong,Bie, Xiaomei
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experimental part
p. 1917 - 1923
(2012/05/19)
-
- Aminolytic reaction catalyzed by d-stereospecific amidohydrolases from Streptomyces spp
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From investigation of 2000 soil isolates, we identified two serine-type amidohydrolases that can hydrolyze d-aminoacyl derivatives from the culture supernatant of Streptomyces species 82F2 and 83D12. The enzymes, redesignated as 82F2-DAP and 83D12-DAP, were purified for homogeneity and characterized. Each enzyme had molecular mass of approximately 40 kDa, and each showed moderate stability with respect to temperature and pH. Among hydrolytic activities toward d-aminoacyl-pNAs, the enzymes showed strict specificity toward d-Phe-pNA, but showed broad specificity toward d-aminoacyl esters. The specific activity for d-Phe-pNA hydrolysis of 82F2-DAP was ten-fold higher than that of 83D12-DAP. As a second function, each enzyme showed peptide bond formation activity by its function of aminolysis reaction. Based on results of d-Phe-d-Phe synthesis under various conditions, we propose a reaction mechanism for d-Phe-d-Phe production. Furthermore, the enzymes exhibited peptide elongation activity, producing oligo homopeptide in a one-pot reaction. We cloned the genes encoding each enzyme, which revealed that the primary structure of each enzyme showed 30-60% identity with those of peptidases belonging to the clan SE, S12 peptidase family categorized as serine peptidase with d-stereospecificity.
- Arima, Jiro,Ito, Hitomi,Hatanaka, Tadashi,Mori, Nobuhiro
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experimental part
p. 1460 - 1469
(2012/01/12)
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- Dynamic kinetic resolution of α-aminonitriles to form chiral α-amino acids
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We have succeeded in the enzymatic synthesis of (R)-α-aminobutyric acid from racemic α-aminobutyronitrile. This has been demonstrated by the use of non-stereoselective nitrile hydratase (NHase) from Rhodococcus opacus 71D, D-aminopeptidase from Ochrobactrum anthropi C1-38 and α-amino-ε- caprolactam (ACL) racemase from Achromobacter obae. Racemic α- aminobutyronitrile was completely converted in 6 h at 30 °C to (R)-α-aminobutyric acid whose optical purity was more than 99%. (S)-α-Aminobutyric acid was also synthesized from α- aminobutyronitrile by NHase, ACL racemase and L-amino acid amidase from Brevundimonas diminuta TPU 5720. In a similar manner, other (R)- or (S)-α-amino acids with more than 97.5% ee could be synthesized from the corresponding α-aminonitriles. This is the first report on the dynamic kinetic resolution (DKR) of α-aminonitriles to form chiral α-amino acids. The key enzyme in this DKR is non-stereoselective NHase, which had been newly screened from soil samples, and its gene cloned. Copyright
- Yasukawa, Kazuyuki,Hasemi, Ryuji,Asano, Yasuhisa
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scheme or table
p. 2328 - 2332
(2011/10/19)
-
- Insecticidal cyclodepsipeptides from beauveria felina
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A novel cyclodepsipeptide, iso-isariin B (1), and the known isaridin E (2) were isolated from the entomopathogenic fungus Beauveria felina. Their structures were elucidated using MS/MS fragmentation and extensive 2D-heteronuclear NMR. The X-ray structure of isaridin E was obtained, showing two potent intramolecular H bonds and a type-VI turn with the HyLeu 1-Pro2 amide bond in a cis conformation. Iso-isariin B (1) was active against the pest-insect Sitophilus spp. with an LD50 value of 10 μg/mL. This observation also gives some clues for ecological interpretation of cyclodepsipeptide production by B. felina.
- Langenfeld, Aude,Blond, Alain,Gueye, Sabelle,Herson, Patrick,Nay, Bastien,Dupont, Jille,Prado, Soizic
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experimental part
p. 825 - 830
(2011/06/19)
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- Revised structure and structure-activity relationship of bisebromoamide and structure of norbisebromoamide from the marine cyanobacterium Lyngbya sp.
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Novel potent cytotoxic peptides bisebromoamide (1) and norbisebromoamide (2) have been isolated from the marine cyanobacterium Lyngbya sp. The planar structure of these peptides was elucidated through the extensive application of 1D and 2D NMR techniques. The absolute stereostructure of 1 was determined by chemical degradation followed by chiral HPLC analysis. Recently, Tao and co-workers achieved synthesis of bisebromoamide, and the configuration of thiazoline moiety was revised. We re-investigated the stereochemistry of thiazoline moiety of 1. The structure-activity relationships of bisebromoamide (1) were investigated with the use of natural and synthetic analogs. Furthermore, bisebromoamide (1) potently inhibited protein kinase: the phosphorylation of ERK in NRK cells by PDGF-stimulation was selectively inhibited by treatment with 10-0.1 μM of 1.
- Sasaki, Hiroaki,Teruya, Toshiaki,Fukazawa, Hidesuke,Suenaga, Kiyotake
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experimental part
p. 990 - 994
(2011/03/19)
-
- Photolysis of rac-leucine with circularly polarized synchrotron radiation
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Amino acids that pass the RNA machinery in living organisms occur in L-configuration. The question on the evolutionary origin of this biomolecular asymmetry remains unanswered to this day. Amino acids were detected in artificially produced interstellar ices, and L-enantiomer-enriched amino acids were identified in CM-type meteorites. This hints at a possible interstellar/circumstellar origin of the amino acids themselves as well as their stereochemical asymmetry. Based upon the current knowledge about the occurrence of circularly-polarized electromagnetic radiation in interstellar environments, we subjected rac-leucine to far-UV circularly-polarized synchrotron radiation. Asymmetric photolysis was followed by an analysis in an enantioselective GC/MS system. Here, we report on an advanced photolysis rate of more than 99% for leucine. The results indicate that high photolysis rates can occur under the chosen conditions, favoring enantioselective photolysis. In 2014, the obtained results will be reexamined by cometary mission Rosetta.
- Meierhenrich, Uwe J.,Filippi, Jean-Jacques,Meinert, Cornelia,Hoffmann, Soren V.,Bredehoeft, Jan Hendrik,Nahon, Laurent
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scheme or table
p. 1651 - 1659
(2011/08/08)
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- Structure, mechanism, and substrate profile for Sco3058: The closest bacterial homologue to human renal dipeptidase
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Human renal dipeptidase, an enzyme associated with glutathione metabolism and the hydrolysis of β-lactams, is similar in sequence to a cluster of ~400 microbial proteins currently annotated as nonspecific dipeptidases within the amidohydrolase superfamily. The closest homologue to the human renal dipeptidase from a fully sequenced microbe is Sco3058 from Streptomyces coelicolor. Dipeptide substrates of Sco3058 were identified by screening a comprehensive series of L-Xaa-L-Xaa, L-Xaa-D-Xaa, and D-Xaa-L-Xaa dipeptide libraries. The substrate specificity profile shows that Sco3058 hydrolyzes a broad range of dipeptides with a marked preference for an L-amino acid at the N-terminus and a D-amino acid at the C-terminus. The best substrate identified was L-Arg-D-Asp (kcat/Km = 7.6 x 105 M -1 s-1). The three-dimensional structure of Sco3058 was determined in the absence and presence of the inhibitors citrate and a phosphinate mimic of L-Ala-D-Asp. The enzyme folds as a (β/α)8 barrel, and two zinc ions are bound in the active site. Site-directed mutagenesis was used to probe the importance of specific residues that have direct interactions with the substrate analogues in the active site (Asp-22, His-150, Arg-223, and Asp-320). The solvent viscosity and kinetic effects of D2O indicate that substrate binding is relatively sticky and that proton transfers do not occurr during the rate-limiting step. A bell-shaped pH-rate profile for kcat and kcat/Km indicated that one group needs to be deprotonated and a second group must be protonated for optimal turnover. Computational docking of high-energy intermediate forms of L/D-Ala-L/D-Ala to the three-dimensional structure of Sco3058 identified the structural determinants for the stereochemical preferences for substrate binding and turnover.
- Cummings, Jennifer A.,Nguyen, Tinh T.,Fedorov, Alexander A.,Kolb, Peter,Xu, Chengfu,Fedorov, Elena V.,Shoichet, Brian K.,Barondeau, David P.,Almo, Steven C.,Raushel, Frank M.
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experimental part
p. 611 - 622
(2011/01/04)
-
- Bisebromoamide, a potent cytotoxic peptide from the marine cyanobacterium lyngbya sp.: Isolation, stereostructure, and biological activity
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A novel cytotoxic peptide, termed bisebromoamide (1), has been Isolated from the marine cyanobacterium Lyngbya sp. Its planar structure was determined by 1D and 2D NMR spectroscopy. The absolute stereostructure of 1 was determined by chemical degradation
- Teruya, Toshiaki,Sasaki, Hiroaki,Fukazawa, Hidesuke,Suenaga, Kiyotake
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supporting information; experimental part
p. 5062 - 5065
(2010/01/06)
-
- SYNTHESIS OF HYBRID BLOCK COPOLYMERS FROM DIFLUOROACETATE AMMONIUM SALTS
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The present invention provides polymerization initiators and uses thereof.
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-
-
- Racemic β-sheets as templates for the generation of homochiral (isotactic) peptides from aqueous solutions of (RS)-valine or -leucine N-carboxy-anhydrides: relevance to biochirogenesis
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As part of our program on biochirogenesis of homochiral peptides from racemic precursors, we report the feasibility of obtaining peptides with homochiral sequences composed of up to 25 residues of the same handedness in the polymerization of racemic valine or leucine N-carboxyanhydrides in aqueous solutions, as initiated by amines. The composition of the oligopeptides was determined by MALDITOF mass spectrometry, and the sequences of some of the heterochiral diastereoisomers were studied by MALDI-TOF MS/MS performed on samples in which the S enantiomers of the monomer were tagged with deuterium atoms. The process comprises several steps: 1) a Markov mechanism of asymmetric induction in the early stages of the polymerization yields libraries of racemic oligopeptides enriched with isotactic diastereoisomers, together with oligopeptide sequences containing enantiomeric blocks of homochiral residues; 2) the short peptides self-assemble into racemic colloidal architectures that serve as regio-enantioselective templates in the ensuing process of chain elongation; 3) homochiral residues of the amino acids located at the periphery of these colloidal aggregates exert efficient enantioselection, which results in the formation of long isotactic oligopeptides. The final diastereoisomeric distribution of the peptides depends upon the composition of the templates, which is determined by the concentration of the initiator. The racemic mixtures of isotactic peptides can be desymmetrized by using enantiopure methyl esters of α-amino acids as initiators.
- Rubinstein, Irina,Clodic, Gilles,Bolbach, Gerard,Weissbuch, Isabelle,Lahav, Meir
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experimental part
p. 10999 - 11009
(2009/11/30)
-
- Regioselective hydration and deprotection of chiral, dissymmetric iminodinitriles in the scope of an asymmetric strecker strategy
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The controlled, selective decomposition of dissymmetric iminodinitriles (DIDN) of formula RCH(CN)-NH-C(CN)R′R″ (considered as N-protected alpha-aminonitriles), is a critical issue for an original asymmetric Strecker strategy previously outlined by us for the enantioselective synthesis of amino acids. This strategy, derived from Harada's work, involves a double sequence of (i) stereoselective Strecker condensation of a chiral ketone R′R″CO with NH3 and HCN, followed by (ii) stereoselective Strecker condensation with an aldehyde RCHO and HCN, then (iii) regioselective retro-Strecker decomposition of the DIDN intermediate to release the target alpha-aminonitrile. In addition to the use of quite simple, cheap cyclic ketones (e.g. carvone derivatives) as chiral auxiliaries, another great advantage of this strategy is that step (iii) enables the recovery of the chiral ketone and hence its reuse. While our previous investigations on step (iii) under various conditions, either preceded or followed by the hydration of the secondary nitrile group RH(CN)- into an amide, had shown insufficient selectivity, we succeeded in the regioselective hydration of the secondary nitrile of DIDN without significant racemisation, by using a large excess of hydrogen peroxide in methanolic/aqueous ammonia (pH 12.5) at low temperature. The resulting imino nitrile/amide compound was then classically decomposed in acidic medium through a retro-Strecker reaction, affording the chiral alpha-amino amide. Alternately, the regioselective retro-Strecker decomposition of the tertiary moiety of the DIDN was achieved by reaction with silver cation in aqueous nitric acid, also without significant racemisation, thus establishing an original, enantioselective synthesis of alpha-aminonitriles. In both reactions, the chiral ketonic auxiliary resulting from DIDN decomposition was recovered in good yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Rossi, Jean-Christophe,Marull, Marc,Boiteau, Laurent,Taillades, Jacques
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p. 662 - 668
(2007/10/03)
-
- Creation of a broad-range and highly stereoselective D-amino acid dehydrogenase for the one-step synthesis of D-amino acids
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Using both rational and random mutagenesis, we have created the first known broad substrate range, nicotinamide cofactor dependent, and highly stereoselective D-amino acid dehydrogenase. This new enzyme is capable of producing D-amino acids via the reductive amination of the corresponding 2-keto acid with ammonia. This biocatalyst was the result of three rounds of mutagenesis and screening performed on the enzyme meso-diaminopimelate D-dehydrogenase. The first round targeted the active site of the wild-type enzyme and produced mutants that were no longer strictly dependent on the native substrate. The second and third rounds produced mutants that had an increased substrate range including straight-and branched-aliphatic amino acids and aromatic amino acids. The very high selectivity toward the D-enantiomer (95 to >99% ee) was shown to be preserved even after the addition of the five mutations found in the three rounds of mutagenesis and screening. This new enzyme could complement and improve upon current methods for D-amino acid synthesis.
- Vedha-Peters, Kavitha,Gunawardana, Manjula,Rozzell, J. David,Novick, Scott J.
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p. 10923 - 10929
(2007/10/03)
-