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Simultaneous Preparation of (S)-2-Aminobutane and d -Alanine or d -Homoalanine via Biocatalytic Transamination at High Substrate Concentration
(S)-2-Aminobutane, d-alanine, and d-homoalanine are important intermediates for the production of various active pharmaceutical ingredients and food additives. The preparation of these small chiral amine or amino acids with high water solubility still demands searching for efficient methods. In this work, we identified an ω-transaminase (ω-TA) from Sinirhodobacter hungdaonensis (ShdTA) that catalyzed the kinetic resolution of racemic 2-aminobutane at a concentration of 800 mM using pyruvate as the amino acceptor, leading to the simultaneous isolation of enantiopure (S)-2-aminobutane and d-alanine in 46% and 90% yield, respectively. In addition, (S)-2-aminobutane (98% ee) and d-homoalanine (99% ee) were isolated in 45% and 93% yield, respectively, in the kinetic resolution of racemic 2-aminobutane at a concentration of 400 mM coupled with deamination of l-threonine by threonine deaminase. We thus developed a biocatalytic process for the practical synthesis of these valuable small chiral amine and d-amino acids.
Li, Jianjiong,Wang, Yingang,Wu, Qiaqing,Yao, Peiyuan,Yu, Shanshan,Zhu, Dunming
supporting information

(2022/03/01)

Powerful Steroid-Based Chiral Selector for High-Throughput Enantiomeric Separation of α-Amino Acids Utilizing Ion Mobility-Mass Spectrometry
Stereospecific recognition of amino acids (AAs) plays a crucial role in chiral biomarker-based diagnosis and prognosis. Separation of AA enantiomers is a long and tedious task due to the requirement of AA derivatization prior to the chromatographic or electrophoretic steps which are also time-consuming. Here, a mass-tagged chiral selector named [d0]/[d5]-estradiol-3-benzoate-17β-chloroformate ([d0]/[d5]-17β-EBC) with high reactivity and good enantiomeric resolution in regard to AAs was developed. After a quick and easy chemical derivatization step of AAs using 17β-EBC as the single chiral selector before ion mobility-mass spectrometry analysis, good enantiomer separation was achieved for 19 chiral proteinogenic AAs in a single analytical run (～2 s). A linear calibration curve of enantiomeric excess was also established using [d0]/[d5]-17β-EBC. It was demonstrated to be capable of determining enantiomeric ratios down to 0.5% in the nanomolar range. 17β-EBC was successfully applied to investigate the absolute configuration of AAs among peptide drugs and detect trace levels of-AAs in complex biological samples. These results indicated that [d0]/[d5]-17β-EBC may contribute to entail a valuable step forward in peptide drug quality control and discovering chiral disease biomarkers.
Li, Yuling,Zhou, Bowen,Wang, Keke,Zhang, Jing,Sun, Wenjian,Zhang, Li,Guo, Yinlong
p. 13589 - 13596
(2021/10/21)

Mechanistic Insight into the Origin of Stereoselectivity in the Ribose-Mediated Strecker Synthesis of Alanine
Enantioenriched amino acids are produced in a hydrolytic kinetic resolution of racemic aminonitriles mediated by chiral pentose sugars. Experimental kinetic and spectroscopic results combined with DFT computational studies and microkinetic modeling help to identify the nature of the intermediate species and provide insight into the stereoselectivity of their hydrolysis in the prebiotically relevant ribose-alanine system. These studies support a synergistic role for sugars and amino acids in the emergence of homochirality in biological molecules.
Legnani, Luca,Darù, Andrea,Jones, Alexander X.,Blackmond, Donna G.
supporting information
p. 7852 - 7858
(2021/05/26)

Structure revision of isocereulide A, an isoform of the food poisoning emetic Bacillus cereus toxin cereulide
The emetic Bacillus cereus toxin cereulide presents an enormous safety hazard in the food industry, inducing emesis and nausea after the consumption of contaminated foods. Additional to cereulide itself, seven structurally related isoforms, namely the isocereulides A-G, have already been elucidated in their chemical structure and could further be identified in B. cereus contaminated food samples. The newly performed isolation of isocereulide A allowed, for the first time, 1D- and 2D-NMR spectroscopy of a biosynthetically produced isocereulide, revealing results that contradict previous assumptions of an L-O-Leu moiety within its chemical structure. By furthermore applying posthydrolytical dipeptide analysis, amino acid and α-hydroxy acid analysis by means of UPLC-ESITOF- MS, as well as MSn sequencing, the structure of previously reported isocereulide A could be corrected. Instead of the L-O-Leu as assumed to date, one L-O-Ile unit could be verified in the cyclic dodecadepsipeptide, revising the structure of isocereulide A to [(D-O-Leu-D-Ala-L-O-Val-L-Val)2(DO- Leu-D-Ala-L-O-Ile-L-Val)].
Ehling-Schulz, Monika,Hofmann, Thomas F.,Kranzler, Markus,Stark, Timo D.,Walser, Veronika
supporting information

(2021/05/31)

Structures and Biosynthetic Pathway of Coprisamides C and D, 2-Alkenylcinnamic Acid-Containing Peptides from the Gut Bacterium of the Carrion Beetle Silpha perforata
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
(2021/02/26)

Targeted Isolation of Asperheptatides from a Coral-Derived Fungus Using LC-MS/MS-Based Molecular Networking and Antitubercular Activities of Modified Cinnamate Derivatives
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
p. 11 - 19
(2021/01/14)

Highly Stable Zr(IV)-Based Metal-Organic Frameworks for Chiral Separation in Reversed-Phase Liquid Chromatography
Separation of racemic mixtures is of great importance and interest in chemistry and pharmacology. Porous materials including metal-organic frameworks (MOFs) have been widely explored as chiral stationary phases (CSPs) in chiral resolution. However, it remains a challenge to develop new CSPs for reversed-phase high-performance liquid chromatography (RP-HPLC), which is the most popular chromatographic mode and accounts for over 90% of all separations. Here we demonstrated for the first time that highly stable Zr-based MOFs can be efficient CSPs for RP-HPLC. By elaborately designing and synthesizing three tetracarboxylate ligands of enantiopure 1,1′-biphenyl-20-crown-6, we prepared three chiral porous Zr(IV)-MOFs with the framework formula [Zr6O4(OH)8(H2O)4(L)2]. They share the same flu topological structure but channels of different sizes and display excellent tolerance to water, acid, and base. Chiral crown ether moieties are periodically aligned within the framework channels, allowing for stereoselective recognition of guest molecules via supramolecular interactions. Under acidic aqueous eluent conditions, the Zr-MOF-packed HPLC columns provide high resolution, selectivity, and durability for the separation of a variety of model racemates, including unprotected and protected amino acids and N-containing drugs, which are comparable to or even superior to several commercial chiral columns for HPLC separation. DFT calculations suggest that the Zr-MOF provides a confined microenvironment for chiral crown ethers that dictates the separation selectivity.
Jiang, Hong,Yang, Kuiwei,Zhao, Xiangxiang,Zhang, Wenqiang,Liu, Yan,Jiang, Jianwen,Cui, Yong
supporting information
p. 390 - 398
(2021/01/13)

Inherently chiral dialkyloxy-calix[4]arene acetic acids as enantiodiscriminating additives for high-performance liquid chromatography separation of d,l-amino acids
Inherently chiral dialkyloxy-calix[4]arene acetic acids with asymmetric placement of substituents on the lower rim of the macrocycle were first studied as enantiodiscriminating additives to the mobile phase MeCN/H2O/HCOOH (75/25/0.02 by volume) in the high-performance liquid chromatography (HPLC) separation of d,l-alanine and d,l-valine on the achiral stationary phase ZORBAX Original CN. The dependence of enantio-binding properties on the position of alkyl groups is demonstrated. The highest resolution (1.65) and enantioselectivity (1.80) were obtained for the 1,2-dipropyloxy-calix[4]arene acetic acid.
Kalchenko, Olga I.,Trybrat, Oleksandr O.,Yesypenko, Oleksandr A.,Dyakonenko, Viktoriya V.,Shishkina, Svitlana V.,Kalchenko, Vitali I.
p. 722 - 730
(2021/08/26)

Exploration of Transaminase Diversity for the Oxidative Conversion of Natural Amino Acids into 2-Ketoacids and High-Value Chemicals
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
p. 7950 - 7957
(2020/08/21)

Zelkovamycins B-E, Cyclic Octapeptides Containing Rare Amino Acid Residues from an Endophytic Kitasatospora sp
Four unusual cyclopeptides, zelkovamycins B-E (1-4), were isolated from an endophytic Kitasatospora sp. Zelkovamycin B was featured by an unprecedented 3-methyl-5-hydroxypyrrolidine-2,4-dione ring system linked to the cyclopeptide skeleton. Their structures and full configurations were established by spectroscopic analysis, Marfey's method, and NMR calculations. A plausible biosynthetic pathway for zelkovamycins was proposed based on gene cluster analysis. Zelkovamycin E displayed potent inhibitory activity against H1N1 influenza A virus.
Cen, Shan,Connolly, Jack A.,Gan, Maoluo,Goss, Rebecca J. M.,Hao, Xiaomeng,Liu, Yufeng,Wang, Yujia,Yu, Jiaqing,Yu, Liyan,Zhang, Yuqin
p. 9346 - 9350
(2020/12/21)

Pagoamide A, a Cyclic Depsipeptide Isolated from a Cultured Marine Chlorophyte, Derbesia sp., Using MS/MS-Based Molecular Networking
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
supporting information

(2020/01/31)

Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce
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
p. 299 - 309
(2019/02/20)

Real-time monitoring of D-Ala-D-Ala dipeptidase activity of VanX in living bacteria by isothermal titration calorimetry
The D,D-dipeptidase enzyme VanX is the main cause of vancomycin resistance in gram-positive bacteria because of hydrolysis of the D-Ala-D-Ala dipeptide used in cell-wall biosynthesis. Continuous assay of VanX has proven challenging due to lack of a chromophoric substrate. Here, we report a direct approach for continuous assay of VanX in vitro and in vivo from hydrolysis of D-Ala-D-Ala, based on the heat-rate changes measured with isothermal titration calorimetry (ITC). With the ITC approach, determination of kinetic parameters of VanX hydrolyzing D-Ala-D-Ala and the inhibition constant of D-cysteine inhibitor yielded KM of 0.10 mM, kcat of 11.5 s?1, and Ki of 18.8 μM, which are consistent with the data from ninhydrin/Cd(II)assays. Cell-based ITC studies demonstrated that the VanX expressed in E. coli and in clinical strain VRE was inhibited by D-cysteine with IC50 values of 29.8 and 28.6 μM, respectively. Also, the total heat from D-Ala-D-Ala (4 mM)hydrolysis decreases strongly (in absolute value)from 1.26 mJ for VRE to 0.031 mJ for E. faecalis, which is consistent with the large MIC value of vancomycin of 512 μg/mL for VRE and the much smaller value of 4 μg/mL for E. faecalis. The ITC approach proposed here could be applied to screen and evaluate small molecule inhibitors of VanX or to identify drug resistant bacteria.
Lv, Miao,Zhang, Yue-Juan,Zhou, Fan,Ge, Ying,Zhao, Mu-Han,Liu, Ya,Yang, Ke-Wu
p. 29 - 35
(2019/05/17)

Cipralphelin, a new anti-oxidative N-cinnamoyl tripeptide produced by the deep sea-derived fungal strain Penicillium brevicompactum FKJ-0123
A new N-cinnamoyl tripeptide, designated cipralphelin (1), was isolated from a cultured broth of Penicillium brevicompactum FKJ-0123 by physicochemical (PC) screening. Compound 1 was purified by silica gel and ODS column chromatography followed by preparative HPLC. The structure of 1 was determined as N-cinnamoyl-prolyl-alanyl-phenylalanine methyl ester by nuclear magnetic resonance and mass spectrometry analyses. The absolute configurations of three amino acids were determined by an advanced Marfey’s method applied to the hydrolysate of 1. Compound 1 was evaluated for its cytotoxicity, anti-microbial activity, and ability to scavenge or quench reactive oxygen species (ROS) such as superoxide anion radicals, hydroxy radicals, and singlet oxygen. Compound 1 exhibited potent scavenging activity against hydroxy radicals.
Matsuo, Hirotaka,Mokudai, Takayuki,Higo, Mayuka,Nonaka, Kenichi,Nagano, Yuriko,Nagahama, Takahiko,Niwano, Yoshimi,Takahashi, Yōko,ōmura, Satoshi,Nakashima, Takuji
p. 775 - 778
(2019/07/29)

Cold-induced aldimine bond cleavage by Tris in: Bacillus subtilis alanine racemase
Pyridoxal 5′-phosphate (PLP) is a versatile cofactor involved in a large variety of enzymatic processes. Most of PLP-catalysed reactions, such as those of alanine racemases (AlaRs), present a common resting state in which the PLP is covalently bound to an active-site lysine to form an internal aldimine. The crystal structure of BsAlaR grown in the presence of Tris lacks this covalent linkage and the PLP cofactor appears deformylated. However, loss of activity in a Tris buffer only occurred after the solution was frozen prior to carrying out the enzymatic assay. This evidence strongly suggests that Tris can access the active site at subzero temperatures and behave as an alternate racemase substrate leading to mechanism-based enzyme inactivation, a hypothesis that is supported by additional X-ray structures and theoretical results from QM/MM calculations. Taken together, our findings highlight a possibly underappreciated role for a common buffer component widely used in biochemical and biophysical experiments.
Bernardo-García, Noelia,Sánchez-Murcia, Pedro A.,Espaillat, Akbar,Martínez-Caballero, Siseth,Cava, Felipe,Hermoso, Juan A.,Gago, Federico
p. 4350 - 4358
(2019/05/10)

One-Pot Preparation of d-Amino Acids Through Biocatalytic Deracemization Using Alanine Dehydrogenase and Ω-Transaminase
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
p. 3678 - 3684
(2018/10/20)

Structure-guided engineering of: Meso -diaminopimelate dehydrogenase for enantioselective reductive amination of sterically bulky 2-keto acids
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
p. 4994 - 5002
(2018/10/17)

Ancistrobrevines E-J and related naphthylisoquinoline alkaloids from the West African liana Ancistrocladus abbreviatus with inhibitory activities against Plasmodium falciparum and PANC-1 human pancreatic cancer cells
From the roots of the West African liana Ancistrocladus abbreviatus (Ancistrocladaceae), ten new naphthylisoquinoline alkaloids (7a, 7b, 8a, 8b, and 9–14), displaying three different coupling types (5,1′, 5,8′, and 7,8′), were isolated, among them a series of five 5,1′-linked representatives and four metabolites belonging to the rare group of 7,8′-coupled alkaloids. Two of the alkaloids, the ancistrobrevines I (13) and J (14), are only the fourth and fifth examples of 7,8′-linked naphthyldihydroisoquinolines ever found in nature. The stereostructures of the new plant metabolites were determined by spectroscopic, chemical (oxidative degradation), and chiroptical (electronic circular dichroism) methods. For the assignment of the axial configuration of 13 and 14 relative to the stereocenter at C-3, which is too far away for significant NOE long-range interactions, these 7,8′-coupled naphthyldihydroisoquinolines were stereoselectively converted into the respective cis-configured tetrahydroisoquinoline analogs. The newly generated ‘auxiliary’ stereocenter at C-1 permitted decisive NOE interactions between the isoquinoline and the naphthalene parts, and thus a reliable attribution of the axial configuration of 13 and 14. In addition, five known compounds (3, 5, 16, 17, and 20), previously discovered in related African and Asian Ancistrocladus species, have now for the first time been identified in A. abbreviatus. All of these alkaloids are S-configured at C-3 and bear an oxygen function at C-6, and are, thus, typical Ancistrocladaceae-type compounds. Some of the alkaloids of A. abbreviatus exhibited promising activities against the malaria parasite Plasmodium falciparum and PANC-1 human pancreatic cancer cells.
Fayez, Shaimaa,Feineis, Doris,Aké Assi, Laurent,Kaiser, Marcel,Brun, Reto,Awale, Suresh,Bringmann, Gerhard
p. 245 - 259
(2018/11/23)

Chiral Metal–Organic Framework Hollow Nanospheres for High-Efficiency Enantiomer Separation
Chiral ZIF-8 hollow nanospheres with d-histidine as part of chiral ligands (denoted as H-d-his-ZIF-8) were prepared for separation of (±)-amine acids. Compared to bulk d-his-ZIF-8 without a hollow cavity, the prepared H-d-his-ZIF-8 showed 15 times higher separation capacity and higher ee values of 90.5 % for alanine, 95.2 % for glutamic acid and 92.6 % for lysine, respectively.
Wang, Xiaoshi,Zhu, Yanan,Liu, Jian,Liu, Chang,Cao, Changyan,Song, Weiguo
p. 1535 - 1538
(2018/06/26)

Enzymatic characterization and crystal structure of biosynthetic alanine racemase from Pseudomonas aeruginosa PAO1
Alanine racemase is a pyridoxal-5′-phosphate (PLP)-dependent enzyme that reversibly catalyzes the conversion of L-alanine to D-alanine. D-alanine is an essential constituent in many prokaryotic cell structures. Inhibition of alanine racemase is lethal to prokaryotes, creating an attractive target for designing antibacterial drugs. Here we report the crystal structure of biosynthetic alanine racemase (Alr) from a pathogenic bacteria Pseudomonas aeruginosa PAO1. Structural studies showed that P. aeruginosa Alr (PaAlr) adopts a conserved homodimer structure. A guest substrate D-lysine was observed in the active site and refined to dual-conformation. Two buffer ions, malonate and acetate, were bound in the proximity to D-lysine. Biochemical characterization revealed the optimal reaction conditions for PaAlr.
Dong, Hui,Han, Qingqing,Guo, Yu,Ju, Jiansong,Wang, Shanshan,Yuan, Chao,Long, Wei,He, Xin,Xu, Shujing,Li, Sheng
p. 2319 - 2325
(2018/07/06)

Chemical constituents isolated from Antarctic marine-derived Aspergillus sp. SF-5976 and their anti-inflammatory effects in LPS-stimulated RAW 264.7 and BV2 cells
Three new benzaldehydes (1–3) and two new dioxopiperazine alkaloids (4 and 5), along with 23 known constituents, were isolated from Antarctic marine-derived Aspergillus sp. SF-5976. Their structures were determined by spectroscopic and chemical methods. Among them, 20 compounds showed inhibitory effects toward lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophages with IC50 values of 7.3–77.4 μM, while 22 compounds did in BV2 microglia with those of 4.6–72.3 μM. Furthermore, the effects of the newly isolated compounds on LPS-stimulated inducible NO synthase (iNOS) expression were investigated, and 1–3, and 5 inhibited iNOS in RAW 264.7 cells, while 1–5 did in BV2 cells. Also, 1–3 and 5 inhibited LPS-induced prostaglandin E2 production with IC50 values of 9.1–66.8 μM in RAW 264.7 macrophages by suppressing cyclooxygenase-2 (COX-2), while in BV2 microglia, 1–5 showed activities with those of 2.8–49.4 μM.
Kwon, Jaeyoung,Lee, Hyaemin,Ko, Wonmin,Kim, Dong-Cheol,Kim, Kwan-Woo,Kwon, Hak Cheol,Guo, Yuanqiang,Sohn, Jae Hak,Yim, Joung Han,Kim, Youn-Chul,Oh, Hyuncheol,Lee, Dongho
p. 3905 - 3912
(2017/06/13)

Cyclombandakamines A1 and A2, Oxygen-Bridged Naphthylisoquinoline Dimers from a Congolese Ancistrocladus Liana
Cyclombandakamines A1 (1) and A2 (2), both with an unprecedented pyrane-cyclohexenone-dihydrofuran sequence and six stereocenters and two chiral axes, are the first oxygen-bridged dimeric naphthylisoquinoline alkaloids. They were isolated from the leaves of an as yet unidentified Congolese Ancistrocladus species. Their stereostructures were established by spectroscopic, chemical, and chiroptical methods in combination with DFT and TDDFT calculations. They apparently originate from a cascade of oxidative cyclization reactions of open-chain naphthylisoquinoline dimers and exhibit significant antiprotozoal activities.
Lombe, Blaise Kimbadi,Bruhn, Torsten,Feineis, Doris,Mudogo, Virima,Brun, Reto,Bringmann, Gerhard
supporting information
p. 1342 - 1345
(2017/03/23)

Chromatographic Resolution of α-Amino Acids by (R)-(3,3'-Halogen Substituted-1,1'-binaphthyl)-20-crown-6 Stationary Phase in HPLC
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
supporting information
p. 1037 - 1042
(2017/07/25)

Neopeapyran, an unusual furo[2,3b]pyran analogue and turnagainolide C from a soil Streptomyces sp. S2236
Neopeapyran (1), an unusual furo[2,3b]pyran analogue, together with a new cyclopeptide, turnagainolide C (2), were isolated from Streptomyces sp. S2236 associated with the rhizosphere soil of Panax notoginseng. The planar structure and relative configuration of neopeapyran (1) were elucidated on the basis of spectroscopic techniques, while the absolute configuration was determined by TDDFT calculation. The absolute configuration of turnagainolide C (2) was determined by partial hydrolysis, together with the advanced Marfey's method and spectroscopic analysis. The antimicrobial activities of these two compounds were also investigated.
Zhou, Hao,Yang, Ya-Bin,Duan, Rong-Ting,Yang, Xue-Qiong,Zhang, Ju-Cheng,Xie, Xiao-Guang,Zhao, Li-Xing,Ding, Zhong-Tao
supporting information
p. 1044 - 1047
(2016/07/29)

New cytotoxic callipeltins from the Solomon Island marine sponge Asteropus sp.
Four new callipeltin A derivatives (N–Q) have been isolated from the Solomon Island marine sponge Asteropus sp. Their structures were established by spectroscopic techniques followed by acid hydrolysis and derivatisation of the free amino acids, and subsequent LCMS analysis of the derivatives. The compounds were evaluated for their activity against cancer cell lines A2058 (melanoma), HT-29 (colorectal adenocarcinoma) and MCF-7 (breast adenocarcinoma) and non-malignant MRC-5 fibroblast cells. While the acyclic callipeltins P and Q were inactive the cyclic callipeltins N and O showed significant cytotoxicity against all exposed cell lines with IC50values as low as 0.16?μM confirming the role of cyclic configuration in biological activity.
Stierhof, Marc,Hansen, Kine ?stnes,Sharma, Mukesh,Feussner, Klaus,Subko, Karolina,Díaz-Rullo, Fernando Fernández,Isaksson, Johan,Pérez-Victoria, Ignacio,Clarke, David,Hansen, Espen,Jaspars, Marcel,Tabudravu, Jioji N.
p. 6929 - 6934
(2016/10/14)

Thermo-responsive adsorption and separation of amino acid enantiomers using smart polymer-brush-modified magnetic nanoparticles
Multifunctional magnetic nanoparticles simultaneously possessing thermo-responsive properties and chiral recognition ability show great potential in enantiomeric separation. In this study, a novel type of multifunctional magnetic Fe3O4 nanoparticle, decorated with smart polymer brushes consisting of poly(N-isopropylacrylamide-co-glycidyl methacrylate) chains with pendent β-cyclodextrin (β-CD) units, was fabricated as a chiral nanoselector for the thermo-sensitive selective adsorption and separation of three amino acid enantiomers. These smart polymer brushes were grafted on the surface of Fe3O4 nanoparticles via a combination of surface-initiated atom transfer radical polymerization and ring-opening reaction. The pendent β-CD units can serve as smart receptors for selectively recognizing enantiomeric molecules via formation of stable host-guest inclusion complexes. The thermo-sensitive poly(N-isopropylacrylamide) chains can act as microenvironmental adjustors for tuning the inclusion constants of β-CD toward enantiomeric guest molecules. The prepared multifunctional magnetic nanoparticles exhibit excellent thermo-responsive adsorption and decomplexation performances toward amino acid enantiomers. Via simply changing the operation temperature, the decomplexation of amino acid enantiomers and regeneration of the smart chiral magnetic nanoparticles can be easily achieved. Besides, the magnetic properties of the regenerated smart nanoparticles enable easy recovery under an external magnetic field for reuse. Such multifunctional magnetic nanoparticles with highly chiral recognition capability, excellent thermo-sensitive adsorption and decomplexation properties toward amino acid enantiomers, and recyclability show great potential in chiral separations.
Song, Ya-Ya,Song, Xiao-Dong,Yuan, Heng,Cheng, Chang-Jing
p. 3194 - 3207
(2016/05/09)

ｔ-BUTYLKETONE BINAPHTHOL DERIVATIVES AND PREPARING METHOD THEREOF
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)

Enantiospecific C-H Activation Using Ruthenium Nanocatalysts
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)

Efficient synthesis of chiral binaphthol aldehyde with phenyl ether linkage for enantioselective extraction of amino acids
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
p. 1834 - 1837
(2015/07/15)

A new cyclic hexapeptide and a new isocoumarin derivative from the marine sponge-associated fungus Aspergillus similanensis KUFA 0013
A new isocoumarin derivative, similanpyrone C (1), a new cyclohexapeptide, similanamide (2), and a new pyripyropene derivative, named pyripyropene T (3) were isolated from the ethyl acetate extract of the culture of the marine sponge-associated fungus Aspergillus similanensis KUFA 0013. The structures of the compounds were established based on 1D and 2D NMR spectral analysis, and in the case of compound 2 the stereochemistry of its amino acid constituents was determined by chiral HPLC analysis of the hydrolysate by co-injection with the D and L amino acids standards. Compounds 2 and 3 were evaluated for their in vitro growth inhibitory activity against MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and A373 (melanoma) cell lines, as well as antibacterial activity against reference strains and the environmental multidrug-resistant isolates (MRS and VRE). Only compound 2 exhibited weak activity against the three cancer cell lines, and neither of them showed antibacterial activity.
Prompanya, Chadaporn,Fernandes, Carla,Cravo, Sara,Pinto, Madalena M. M.,Dethoup, Tida,Silva, Artur M. S.,Kijjoa, Anake
p. 1432 - 1450
(2015/04/14)

Deracemization of amino acids by coupling transaminases of opposite stereoselectivity
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
p. 3505 - 3509
(2015/02/19)

Cyclic lipodepsipeptides verlamelin A and B, isolated from entomopathogenic fungus Lecanicillium sp.
Verlamelin and its new derivative (verlamelin B) were isolated from fermentation broth of entomopathogenic fungus Lecanicillium sp. HF627. As the structural elucidation of verlamelin so far was only preliminary, we studied and determined the absolute structure of these two compounds to be cyclo(5S-hydroxytetradecanoic acid-D-alloThr/Ser-D-Ala-L-Pro-L-Gln-D-Tyr-L-Val). This is the first study that precisely analyzed the structure of verlamelin.
Ishidoh, Kei-Ichi,Kinoshita, Hiroshi,Igarashi, Yasuhiro,Ihara, Fumio,Nihira, Takuya
p. 459 - 463
(2014/07/08)

Balgacyclamides, antiplasmodial heterocyclic peptides from Microcystis aeruguinosa EAWAG 251
The isolation and structural characterization of three new heterocyclic and macrocyclic peptides, balgacyclamides A-C, from Microcystis aeruginosa EAWAG 251 are reported. The constitutions were determined by 2D-NMR methods and mass spectrometry, and the configurations were assigned after ozonolysis and hydrolysis by HPLC-MS methods using Marfey's method as well as GC-MS using authentic standards. Balgacyclamides A and B were active against Plasmodium falciparum K1 in the low micromolar range, while displaying low toxicity to rat myoblasts.
Portmann, Cyril,Sieber, Simon,Wirthensohn, Silvan,Blom, Judith F.,Da Silva, Laeticia,Baudat, Emilie,Kaiser, Marcel,Brun, Reto,Gademann, Karl
p. 557 - 562
(2014/04/17)

SEPARATING AGENT AND MANUFACTURING METHOD THEREOF
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; 0077; 0078

(2015/01/07)

Immobilization of optically active helical polyacetylene-derived nanoparticles on graphene oxide by chemical bonds and their use in enantioselective crystallization
The present study originally created a methodology for immobilizing polymeric nanoparticles on graphene oxide (GO) by chemical bonds, aiming at chiral functionalization of GO and simultaneously improving the dispersibility of polymer nanoparticles. To prepare the novel GO hybrids, GO was first prepared and alkynylated to form an actual comonomer (MGO), in the presence of which acetylenic monomer (M1) underwent emulsion polymerization in aqueous media with sodium dodecyl sulfate as emulsifier and (nbd)Rh +B-(C6H5)4 as catalyst. SEM and HRTEM images ascertained the formation of polymeric nanoparticles immobilized on GO (NPpoly1/GO). CD and UV-vis absorption spectra demonstrated the optical activity of NPpoly1/GO, originated from the chiral helical conformations adopted by the polymer chains constructing the nanoparticles. FT-IR, Raman, XPS, XRD, and TGA techniques were also utilized to characterize the GO hybrids. The as-obtained NPpoly1/GO was further used as a chiral additive to perform enantioselective crystallization of l-alanine from racemic alanine. l-Alanine was preferentially induced to crystallize rod-like crystals, according to SEM, CD, and XRD characterizations. The present study provides a versatile platform for preparing GO-derived functional materials, particularly novel chiral materials.
Li, Weifei,Liu, Xuan,Qian, Guangyue,Deng, Jianping
p. 1948 - 1956
(2014/04/03)

ω-Transaminase-catalyzed asymmetric synthesis of unnatural amino acids using isopropylamine as an amino donor
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
p. 6929 - 6933
(2013/10/08)

Biocatalytic asymmetric synthesis of unnatural amino acids through the cascade transfer of amino groups from primary amines onto keto acids
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
p. 3538 - 3542
(2014/01/06)

Champacyclin, a new cyclic octapeptide from Streptomyces strain C42 isolated from the Baltic Sea
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.
p. 4834 - 4857
(2014/02/14)

Homosecoiridoid alkaloids with amino acid units from the flower buds of lonicera japonica
Nine new homosecoiridoid alkaloids, named lonijaposides O-W (1-9), along with 19 known compounds, were isolated from an aqueous extract of the flower buds of Lonicera japonica. Their structures and absolute configurations were determined by spectroscopic data analysis and chemical methods. Lonijaposides O-W have structural features that involve amino acid units sharing the N atom with a pyridinium (1-5) or nicotinic acid (6-9) moiety. The absolute configurations of the amino acid units were determined by oxidation of each pyridinium ring moiety with potassium ferricyanide, hydrolysis of the oxidation product, and Marfey's analysis of the hydrolysate. This procedure was validated by oxidizing and hydrolyzing synthetic model compounds. The phenylalanine units in compounds 4, 5, and 9 have the d-configuration, and the other amino acid units in 1-3 and 6-8 possess the l-configuration. Compounds 1, 4, 6, and 9 and the known compounds 3,4-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 5′-O-methyladenosine exhibited antiviral activity against the influenza virus A/Hanfang/359/95 (H3N2) with IC50 values of 3.4-11.6 μM, and 4 inhibited Coxsackie virus B3 replication with an IC50 value of 12.3 μM.
Yu, Yang,Zhu, Chenggen,Wang, Sujuan,Song, Weixia,Yang, Yongchun,Shi, Jiangong
p. 2226 - 2233
(2014/01/17)

Structure and biosynthesis of xenoamicins from entomopathogenic xenorhabdus
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.
supporting information
p. 16772 - 16779
(2014/01/06)

Characterization of d-amino acid aminotransferase from Lactobacillus salivarius
We searched a UniProt database of lactic acid bacteria in an effort to identify d-amino acid metabolizing enzymes other than alanine racemase. We found a d-amino acid aminotransferase (d-AAT) homologous gene (UniProt ID: Q1WRM6) in the genome of Lactobacillus salivarius. The gene was then expressed in Escherichia coli, and its product exhibited transaminase activity between d-alanine and α-ketoglutarate. This is the first characterization of a d-AAT from a lactic acid bacterium. L. salivarius d-AAT is a homodimer that uses pyridoxal-5′-phosphate (PLP) as a cofactor; it contains 0.91 molecules of PLP per subunit. Maximum activity was seen at a temperature of 60 °C and a pH of 6.0. However, the enzyme lost no activity when incubated for 30 min at 30 °C and pH 5.5 to 9.5, and retained half its activity when incubated at pH 4.5 or 11.0 under the same conditions. Double reciprocal plots of the initial velocity and d-alanine concentrations in the presence of several fixed concentrations of α-ketoglutarate gave a series of parallel lines, which is consistent with a Ping-Pong mechanism. The Km values for d-alanine and α-ketoglutarate were 1.05 and 3.78 mM, respectively. With this enzyme, d-allo-isoleucine exhibited greater relative activity than d-alanine as the amino donor, while α-ketobutylate, glyoxylate and indole-3-pyruvate were all more preferable amino acceptors than α-ketoglutarate. The substrate specificity of L. salivarius d-AAT thus differs greatly from those of the other d-AATs so far reported.
Kobayashi, Jyumpei,Shimizu, Yasuhiro,Mutaguchi, Yuta,Doi, Katsumi,Ohshima, Toshihisa
p. 15 - 22
(2013/10/22)

Reusable ω-transaminase sol-gel catalyst for the preparation of amine enantiomers
Heterogeneous ω-transaminase sol-gel catalysts were prepared and characterized in terms of immobilization degree, loading capacity and catalytic behavior in the kinetic resolution of racemic 1-phenylethylamine (a model compound) with sodium pyruvate in phosphate buffer (pH 7.5). The catalyst obtained when ω-transaminase from Arthrobacter sp. was encapsulated from the aqueous solution of the enzyme, isopropyl alcohol and polyvinyl alcohol in the sol-gel matrices, consisting of the 1:5 mixture of tetramethoxysilane and methyltrialkoxysilane, proved to be optimal including the reuse and storage stabilities of the catalyst. The optimized immobilizate was shown to perform well in the kinetic resolution of four structurally different aromatic primary amines in aqueous DMSO (10, v/v-%). The enzyme preparation showed synthetic potential by enabling the catalyst reuse in five consecutive preparative scale kinetic resolutions using 100 mM 1-phenylethylamine in aqueous DMSO (10, v/v-%). It was typical to fresh catalyst preparations that the kinetic resolution tended to exceed 50% before the reaction stopped leaving the (S)-amine unreacted while thereafter in reuse the reactions stopped at 50% conversion as expectable to highly enantioselective reactions.
P?ivi?, Mari,Kanerva, Liisa T.
p. 1488 - 1494
(2013/09/24)

Asperterrestide A, a cytotoxic cyclic tetrapeptide from the marine-derived fungus Aspergillus terreus SCSGAF0162
A new cytotoxic and antiviral cyclic tetrapeptide, asperterrestide A (1), a new alkaloid, terremide C (2), and a new aromatic butenolide, aspernolide E (3), together with 10 known compounds were isolated from the fermentation broth of the marine-derived fungus Aspergillus terreus SCSGAF0162. Their structures were elucidated by spectroscopic analysis, and the absolute configuration of 1 was determined by the Mosher ester technique and analysis of the acid hydrolysates using a chiral-phase HPLC column. Compound 1 contains a rare 3-OH-N-CH3-Phe residue and showed cytotoxicity against U937 and MOLT4 human carcinoma cell lines and inhibitory effects on influenza virus strains H1N1 and H3N2.
He, Fei,Bao, Jie,Zhang, Xiao-Yong,Tu, Zheng-Chao,Shi, Yi-Ming,Qi, Shu-Hua
supporting information
p. 1182 - 1186
(2013/07/26)

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
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
p. 6746 - 6750
(2013/07/26)

Chemical approach for interconversion of (S)- and (R)-α-amino acids
Here we report a general method for the preparation of unnatural (R)-α-amino acids via complexation of α-(phenyl)ethylamine derived chiral reagent (S)-3 with various (S)-α-amino acids. The reactions proceed with synthetically useful chemical yields and thermodynamically controlled diastereoselectivity. Chiral reagent (S)-3 can be conveniently recovered and reused without any loss of enantiomeric purity and reactivity. The Royal Society of Chemistry 2013.
Sorochinsky, Alexander E.,Ueki, Hisanori,Ace?a, José Luis,Ellis, Trevor K.,Moriwaki, Hiroki,Sato, Tatsunori,Soloshonok, Vadim A.
p. 4503 - 4507
(2013/08/23)

SEPARATING AGENT FOR CHROMATOGRAPHY
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.
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Paragraph 0074; 0075

(2013/08/15)

O-Seco-RA-XXIV, a possible precursor of an antitumor peptide RA-XXIV, from Rubia cordifolia L.
O-Seco-RA-XXIV, a new cyclic peptide, cyclo-(d-alanyl-l-glutaminyl-N,O- dimethyl-l-tyrosyl-l-alanyl-N-methyl-l-tyrosyl-N-methyl-l-tyrosyl), was isolated from the roots of Rubia cordifolia L. along with RA-XXIV. Its structure and relative stereochemistry were determined by interpretation of the spectroscopic data and X-ray crystallography, and its absolute stereochemistry by the Marfey's amino acid analysis of its acid hydrolysate. Isolation of the two peptides from the same plant source may indicate that O-seco-RA-XXIV is a possible precursor of RA-XXIV and that the formation of the diphenyl ether linkage in the cycloisodityrosine moiety is to be formed after the formation of the cyclohexapeptide chain in this series of peptides.
Hitotsuyanagi, Yukio,Kusano, Jun-Ichi,Kim, Ik-Hwi,Hasuda, Tomoyo,Fukaya, Haruhiko,Takeya, Koichi
experimental part
p. 335 - 339
(2012/07/27)

MULTIMER GLYCOSYLATED NUCLEIC ACID BINDING PROTEIN CONJUGATES AND USES THEREOF
The technology relates in part to multimer conjugates comprising a scaffold linked to two or more polypeptides that specifically interact with a nucleic acid containing beta-D-glucosyl-hydroxymethylcytosine or beta-D-glucosyl-hydroxymethyluracil. The scaffold can be chosen from an antibody, an antibody fragment, a multimerized binding partner that interacts with a binding partner counterpart in each of the polypeptides, a polymer, and a polyfunctional molecule. The polypeptides can be from a kinetoplastid flagellate organism and may comprise a full-length native or modified protein or a fragment thereof that specifically interacts with the beta-D-glucosyl-hydroxymethylcytosine and/or the beta-D-glucosyl-hydroxymethyluracil in the nucleic acid. The conjugates provided herein can be used to detect the presence, absence or amount of beta-D-glucosyl-hydroxymethylcytosine and/or beta-D-glucosyl-hydroxymethyluracil-containing nucleic acid in a sample.
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(2012/11/08)

Enantioselective solid-phase peptide synthesis using traceless chiral coupling reagents and racemic amino acids
The enantioselective condensing reagent 4,6-dimethoxy-1,3,5-triazine (DMT)/strychnine/BF-4 was obtained by treatment of 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) with strychnine tetrafluoroborate. The reagent was useful under typical conditions of solid-phase peptide synthesis (SPPS) with enantiomerically homogeneous substrates. By SPPS, desired dipeptides were obtained in 84-94% yield using 4 equiv. of racemic Fmoc-Ala, Fmoc-Phe, and/or Fmoc-Tyr for 1 equiv. of Wang resin loaded with Gly, Ala, Leu, Phe, Glu(tBu), and/or Pro, respectively. For all three Fmoc-protected amino acids, the configuration of the enantiomer preferred under SPPS conditions was independent of the structure of the acylated component and identical to that established in condensations proceeding in solution. In all cases, the enantiomer ratios L/D (er) were in a similar range, and varied from 9: 92 to 2: 98 for alanine, and from 90: 10 to 100: 0 for aromatic amino acids. The synthesis of Ac-L-Lys(Ac)-D-Ala-D-Ala-OH from racemic Fmoc-Ala gave an L/D ratio of 10: 90 for the esterification of Wang resin, and 0: 100 for the formation of peptide bonds.
Kolesinska, Beata,Kasperowicz-Frankowska, Katarzyna,Fraczyk, Justyna,Kaminski, Zbigniew J.
p. 2084 - 2098
(2013/02/23)

Luminmycins A-C, cryptic natural products from Photorhabdus luminescens identified by heterologous expression in Escherichia coli
The 18 kb silent luminmycin biosynthetic pathway from Photorhabdus luminescens was cloned into a vector by using the newly established linear-linear homologous recombination and successfully expressed in Escherichia coli. Luminmycins A-C (1-3) were isolated from the heterologous host, and their structures were elucidated using 2D NMR spectroscopy and HRESIMS. Luminmycin A is a deoxy derivative of the previously reported glidobactin A, while luminmycins B and C most likely represent its acyclic biosynthetic intermediates. Compound 1 showed cytotoxicity against the human colon carcinoma HCT-116 cell line with an IC50 value of 91.8 nM, while acyclic 2 was inactive at concentrations as high as 100 μg/mL.
Bian, Xiaoying,Plaza, Alberto,Mueller, Rolf,Zhang, Youming
p. 1652 - 1655,4
(2020/09/09)