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Enhanced carboxypeptidase efficacies and differentiation of peptide epimers
Carboxypeptidases enzymatically cleave the peptide bond of C-terminal amino acids. In humans, it is involved in enzymatic synthesis and maturation of proteins and peptides. Carboxypeptidases A and Y have difficulty hydrolyzing the peptide bond of dipeptides and some other amino acid sequences. Early investigations into different N-blocking groups concluded that larger moieties increased substrate susceptibility to peptide bond hydrolysis with carboxypeptidases. This study conclusively demonstrates that 6-aminoquinoline-N-hydroxysuccimidyl carbamate (AQC) as an N-blocking group greatly enhances substrate hydrolysis with carboxypeptidase. AQC addition to the N-terminus of amino acids and peptides also improves chromatographic peak shapes and sensitivities via mass spectrometry detection. These enzymes have been used for amino acid sequence determination prior to the advent of modern proteomics. However, most modern proteomic methods assume that all peptides are comprised of L-amino acids and therefore cannot distinguish L-from D-amino acids within the peptide sequence. The majority of existing methods that allow for chiral differentiation either require synthetic standards or incur racemization in the process. This study highlights the resistance of D-amino acids within peptides to enzymatic hydrolysis by Carboxypeptidase Y. This stereoselectivity may be advantageous when screening for low abundance peptide stereoisomers.
Sung, Yu-Sheng,Putman, Joshua,Du, Siqi,Armstrong, Daniel W.
(2022/01/29)

Recreating the natural evolutionary trend in key microdomains provides an effective strategy for engineering of a thermomicrobial N-demethylase
N-demethylases have been reported to remove the methyl groups on primary or secondary amines, which could further affect the properties and functions of biomacromolecules or chemical compounds; however, the substrate scope and the robustness of N-demethylases have not been systematically investigated. Here we report the recreation of natural evolution in key microdomains of the Thermomicrobium roseum sarcosine oxidase (TrSOX), an N-demethylase with marked stability (melting temperature over 100 C) and enantioselectivity, for enhanced substrate scope and catalytic efficiency on -C-N-bonds. We obtained the structure of TrSOX by crystallization and X-ray diffraction (XRD) for the initial framework. The natural evolution in the nonconserved residues of key microdomains—including the catalytic loop, coenzyme pocket, substrate pocket, and entrance site—was then identified using ancestral sequence reconstruction (ASR), and the substitutions that accrued during natural evolution were recreated by site-directed mutagenesis. The single and double substitution variants catalyzed the N-demethylation of N-methyl-L-amino acids up to 1800- and 6000-fold faster than the wild type, respectively. Additionally, these single substitution variants catalyzed the terminal N-demethylation of non-amino-acid compounds and the oxidation of the main chain -C-N- bond to a -C=N- bond in the nitrogen-containing heterocycle. Notably, these variants retained the enantioselectivity and stability of the initial framework. We conclude that the variants of TrSOX are of great potential use in N-methyl enantiomer resolution, main-chain Schiff base synthesis, and alkaloid modification or degradation.
Gu, Zhenghua,Guo, Zitao,Shao, Jun,Shen, Chen,Shi, Yi,Tang, Mengwei,Xin, Yu,Zhang, Liang
(2022/03/09)

Direct monitoring of biocatalytic deacetylation of amino acid substrates by1H NMR reveals fine details of substrate specificity
Amino acids are key synthetic building blocks that can be prepared in an enantiopure form by biocatalytic methods. We show that thel-selective ornithine deacetylase ArgE catalyses hydrolysis of a wide-range ofN-acyl-amino acid substrates. This activity was revealed by1H NMR spectroscopy that monitored the appearance of the well resolved signal of the acetate product. Furthermore, the assay was used to probe the subtle structural selectivity of the biocatalyst using a substrate that could adopt different rotameric conformations.
De Cesare, Silvia,McKenna, Catherine A.,Mulholland, Nicholas,Murray, Lorna,Bella, Juraj,Campopiano, Dominic J.
supporting information
p. 4904 - 4909
(2021/06/16)

A novel phenylalanine ammonia-lyase from Pseudozyma antarctica for stereoselective biotransformations of unnatural amino acids
A novel phenylalanine ammonia-lyase of the psychrophilic yeast Pseudozyma antarctica (PzaPAL) was identified by screening microbial genomes against known PAL sequences. PzaPAL has a significantly different substrate binding pocket with an extended loop (26 aa long) connected to the aromatic ring binding region of the active site as compared to the known PALs from eukaryotes. The general properties of recombinant PzaPAL expressed in E. coli were characterized including kinetic features of this novel PAL with L-phenylalanine (S)-1a and further racemic substituted phenylalanines rac-1b-g,k. In most cases, PzaPAL revealed significantly higher turnover numbers than the PAL from Petroselinum crispum (PcPAL). Finally, the biocatalytic performance of PzaPAL and PcPAL was compared in the kinetic resolutions of racemic phenylalanine derivatives (rac-1a-s) by enzymatic ammonia elimination and also in the enantiotope selective ammonia addition reactions to cinnamic acid derivatives (2a-s). The enantiotope selectivity of PzaPAL with o-, m-, p-fluoro-, o-, p-chloro- and o-, m-bromo-substituted cinnamic acids proved to be higher than that of PcPAL.
Varga, Andrea,Csuka, Pál,Sonesouphap, Orlavanah,Bánóczi, Gergely,To?a, Monica Ioana,Katona, Gabriel,Molnár, Zsófia,Bencze, László Csaba,Poppe, László,Paizs, Csaba
p. 185 - 194
(2020/04/28)

Mechanically Strong Heterogeneous Catalysts via Immobilization of Powderous Catalysts to Porous Plastic Tablets
Main observation and conclusion: We describe a practical and general protocol for immobilization of heterogeneous catalysts to mechanically robust porous ultra-high molecular weight polyethylene tablets using inter-facial Lifshitz-van der Waals Interactions. Diverse types of powderous catalysts, including Cu, Pd/C, Pd/Al2O3, Pt/C, and Rh/C have been immobilized successfully. The immobilized catalysts are mechanistically robust towards stirring in solutions, and they worked well in diverse synthetic reactions. The immobilized catalyst tablets are easy to handle and reused. Moreover, the metal leaching of immobilized catalysts was reduced significantly.
Li, Tingting,Xu, Bo
supporting information
p. 2673 - 2678
(2021/08/03)

SUPRAMOLECULAR GEL SUPPORTED ON OPEN-CELL POLYMER FOAM
The present invention relates to a polymer foam, said polymer foam comprising pores forming an open-cell polymer foam, said polymer foam comprising a supramolecular gel inside pores, and said polymer foam comprising at least one enzyme. The present invention relates to a supramolecular gel; its preparation and its applications, notably in chemical synthesis and kinetic resolution, in particular of organic compounds. The present invention also relates to flow chemistry.
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(2021/03/19)

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)

Investigation of Taniaphos as a chiral selector in chiral extraction of amino acid enantiomers
Finding chiral selector with high stereoselectivity to a variety of amino acid enantiomers remains a challenge and warrants further research. In this work, Taniaphos, a chiral ligand with rotatable spatial configuration, was employed as a chiral extractant to enantioseparate various amino acid enantiomers. Phenylalanine (Phe), homophenylalanine (Hphe), 4-nitrophenylalanine (Nphe), and 3-chloro-phenylglycine (Cpheg) were used as substrates to evaluate the extraction efficiency. The results revealed that Taniaphos-Cu exhibited good abilities to enantioseparate Phe, Hphe, Nphe, and Cpheg with the highest separation factors (α) of 3.13, 2.10, 2.32, and 2.14, respectively. Taniaphos-Cu is more conducive to combine with D-amino acid in extraction. The influences of pH, Taniaphos-Cu, and concentration and extraction temperature on extraction were comprehensively evaluated. The highest performance factors (pf) for Phe, Hphe, Nphe, and Cpheg at optimal extraction conditions were 0.08892, 0.1250, 0.09621, and 0.08021, respectively. The recognition mechanism between Taniaphos-Cu and amino acid enantiomers was discussed. The coordination interaction between Taniaphos-Cu and -COO?, π-π interaction between Taniaphos-Cu and amino acid enantiomers are important acting forces in chiral extraction. The steric-hindrance between -NH2 and -OH lead to Taniaphos-Cu-D-Phe is more stable than Taniaphos-Cu-L-Phe. This work provided a chiral extractant that has good abilities to enantioseparate various amino acid enantiomers.
Xiao, Wenjie,Chen, Shuhuan,Liu, Xiong,Ma, Yu
p. 292 - 302
(2021/03/29)

Reconstruction of Hyper-Thermostable Ancestral L-Amino Acid Oxidase to Perform Deracemization to D-Amino Acids
L-amino acid oxidases (LAAOs) with broad substrate specificity can be used in the deracemization of D,L-amino acids (D,L-AAs) to their D-enantiomers. Hyper-thermostable LAAO (HTAncLAAO) was designed through a combination of manual sequence data mining and ancestral sequence reconstruction. Soluble expression of HTAncLAAO (>50 mg/L) can be achieved using an E. coli system. HTAncLAAO, which recognizes seven L-AAs as substrates, exhibits extremely high thermal stability and long-term stability; the t1/2 value was 95 °C and 99 % ee, D-enantiomer). These results suggest that HTAncLAAO is an excellent biocatalyst to perform this deracemization.
Ishida, Chiharu,Miyata, Ryo,Hasebe, Fumihito,Miyata, Azusa,Kumazawa, Shigenori,Ito, Sohei,Nakano, Shogo
p. 5228 - 5235
(2021/11/05)

Steps towards sustainable solid phase peptide synthesis: use and recovery ofN-octyl pyrrolidone
The investigation of new green biogenic pyrrolidinones as alternative solvents toN,N-dimethylformamide (DMF) for solid phase peptide synthesis (SPPS) led to the identification ofN-octyl pyrrolidone (NOP) as the best candidate. NOP showed good performances in terms of swelling, coupling efficiency and low isomerization generating peptides with very high purity. A mixture of NOP with 20% dimethyl carbonate (DMC) allowed a decrease in solvent viscosity, making the mixture suitable for the automated solid-phase protocol. Aib-enkephalin and linear octreotide were successfully used to test the methodologies. It is worth noting that NOP, DMC and the piperidine used in the deprotection step could be easily recovered by direct distillation from the process waste mixture. The process mass intensity (PMI), being reduced by 63-66%, achieved an outstanding value representing a clear step forward in achieving green SPPS.
Martelli, Giulia,Cantelmi, Paolo,Tolomelli, Alessandra,Corbisiero, Dario,Mattellone, Alexia,Ricci, Antonio,Fantoni, Tommaso,Cabri, Walter,Vacondio, Federica,Ferlenghi, Francesca,Mor, Marco,Ferrazzano, Lucia
supporting information
p. 4095 - 4106
(2021/06/17)

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)

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)

Genomics-driven discovery of a new cyclodepsipeptide from the guanophilic fungusAmphichorda guana
Two potential non-ribosomal peptide synthetases (NRPSs) were identified in the genome of a guanophilic fungusAmphichorda guanaby bioinformatics analysis and gene knockout experiments. Liquid chromatography coupled with mass spectrometry (LC-MS) guided isolation led to the discovery of a new cyclodepsipeptide isaridin H (1) and seven known analogs, desmethylisaridin E (2), isaridin E (3), isariin A (4), iso-isariin B (5), iso-isariin D (6), isariin E (7), and nodupetide (8). The absolute configuration of isaridin H (1) was achieved by Marfey's method. Isaridin H (1) showed significant antifungal activity againstBotrytis cinereaandAlternaria solani.
Liang, Min,Lyu, Hai-Ning,Ma, Zi-Ying,Li, Er-Wei,Cai, Lei,Yin, Wen-Bing
p. 1960 - 1964
(2021/03/16)

Komesuamide and odopenicillatamide, two linear lipopeptides from the marine cyanobacterium Caldora penicillata
The linear lipopeptides komesuamide (1) and odopenicillatamide (2) were isolated from Caldora penicillata a marine cyanobacterium collected in Okinawa. The structures of these compounds were established by spectroscopic analyses, and the absolute configurations were determined by HPLC analyses of the acid hydrolysates. Both compounds showed glucose uptake activity at 40 μM in cultured L6 myotubes.
Ozaki, Kaori,Jinno, Atsuhide,Natsume, Noriyuki,Sumimoto, Shimpei,Iwasaki, Arihiro,Suenaga, Kiyotake,Teruya, Toshiaki
(2021/04/05)

Argicyclamides A-C Unveil Enzymatic Basis for Guanidine Bis-prenylation
Guanidine prenylation is an outstanding modification in alkaloid and peptide biosynthesis, but its enzymatic basis has remained elusive. We report the isolation of argicyclamides, a new class of cyanobactins with unique mono- and bis-prenylations on guanidine moieties, from Microcystis aeruginosa NIES-88. The genetic basis of argicyclamide biosynthesis was established by the heterologous expression and in vitro characterization of biosynthetic enzymes including AgcF, a new guanidine prenyltransferase. This study provides important insight into the biosynthesis of prenylated guanidines and offers a new toolkit for peptide modification.
Balloo, Nandani,Fujita, Kei,Matsuda, Kenichi,Okino, Tatsufumi,Phan, Chin-Soon,Wakimoto, Toshiyuki
supporting information
p. 10083 - 10087
(2021/07/26)

Method for photolysis of amido bonds
The invention discloses a method for photo-splitting amido bonds, wherein the method is mild in reaction condition and can realize splitting of amido bonds by using illumination. The method for photo-splitting the amido bonds comprises the following steps: reacting 2,4-dinitrofluorobenzene with an amino group of a substance which contains alpha amino acid at the tail end and is shown as a structural formula I to generate a compound 1 represented by a structural formula II; and under light irradiation, carrying out amido bond cleavage reaction on the compound 1, wherein R1 is a side chain group of alpha-amino acid, and R2 is aryl, aliphatic hydrocarbon, -CH(R)-COOH or polypeptide.
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Paragraph 0046; 0048-0049; 0058-0061

(2021/06/26)

Purification and Characterization of Anabaena flos-aquae Phenylalanine Ammonia-Lyase as a Novel Approach for Myristicin Biotransformation
Phenylalanine ammonia-lyase (PAL) catalyzes the reversible deamination of phenylalanine to cinnamic acid and ammonia. Algae have been considered as biofactories for PAL production, however, biochemical characterization of PAL and its potency for myristicin biotransformation into MMDA (3-methoxy-4, 5-methylenedioxyamphetamine) has not been studied yet. Thus, PAL from Anabaena flos-aquae and Spirulina platensis has been purified, comparatively characterized and its affinity to transform myristicin was assessed. The specific activity of purified PAL from S. platensis (73.9 μmol/mg/min) and A. flos-aquae (30.5 μmol/mg/min) was increased by about 2.9 and 2.4 folds by gel-filtration comparing to their corresponding crude enzymes. Under denaturing-PAGE, a single proteineous band with a molecular mass of 64 kDa appeared for A. flos-aquae and S. platensis PAL. The biochemical properties of the purified PAL from both algal isolates were determined comparatively. The optimum temperature of S. platensis and A. flos-aquae PAL for forward or reverse activity was reported at 30oC, while the optimum pH for PAL enzyme isolated from A. flos-aquae was 8.9 for forward and reverse activities, and S. platensis PAL had maximum activities at pH 8.9 and 8 for forward and reverse reactions, respectively. Luckily, the purified PALs have the affinity to hydroaminate the myristicin to MMDA successfully in one step. Furthermore, a successful method for synthesis of MMDA from myristicin in two steps was also established. Gas chromatography-mass spectrometry (GC-MS) analysis was conducted to track the product formation.
Abdel-Ghany, Afaf E.,Abdelaziz, Sahar,Arafa, Asmaa M.,El-Ayouty, Yassin,El-Dahmy, Samih I.,El-Sayed, Ashraf S. A.
p. 622 - 632
(2020/05/08)

Nickel-Catalyzed Asymmetric Hydrogenation of 2-Amidoacrylates
Earth-abundant nickel, coordinated with a suitable chiral bisphosphine ligand, was found to be an efficient catalyst for the asymmetric hydrogenation of 2-amidoacrylates, affording the chiral α-amino acid esters in quantitative yields and excellent enantioselectivity (up to 96 % ee). The active catalyst component was studied by NMR and HRMS, which helped us to realize high catalytic efficiency on a gram scale with a low catalyst loading (S/C=2000). The hydrogenated products could be simply converted into chiral α-amino acids, β-amino alcohols, and their bioactive derivatives. Furthermore, the catalytic mechanism was investigated using deuterium-labeling experiments and computational calculations.
Chen, Jianzhong,Gridnev, Ilya D.,Hu, Yawen,Li, Bowen,Zhang, Wanbin,Zhang, Zhenfeng
supporting information
p. 5371 - 5375
(2020/02/15)

Asymmetric synthesis, biological activity and molecular docking studies of some unsaturated α-amino acids, derivatives of glycine, allylglycine and propargylglycine
New enantiomerically enriched unsaturated tailor-made amino acids have been obtained. As a starting amino acid synthon for the asymmetric synthesis of tailor-made unsaturated amino acids, Ni(II) square-planar complexes of Schiff's bases of propargylglycine, allylglycine and glycine with chiral auxiliary (S)-2-N-(N’-benzylprolyl)-aminobenzophenone ((S)-BPB) were used. The Cα-alkylation of propargylglycine, allylglycine and glycine moieties resulted in the asymmetric synthesis of novel (S)-α-propargylglycine, (S)-α-allylglycine and glycine derivatives containing an aromatic group in the side chain (de 80–95,5%). After purification and cleavage of the metal complexes, the amino acids were isolated in high enantiomeric purity (ee >99%). Of the obtained seven tailor-made amino acids four showed inhibitory activity to collagenase G. The amino acid with an acetylene bond in the side chain (IC50 = 1.29 ± 0.02 mM) had the best result. Molecular docking showed that the amino acids with activity to collagenase G contained hydrogen and π-π bonds with the enzyme.
Hayriyan, Liana A.,Karapetyan, Ani J.,Minasyan, Ella V.,Mkrtchyan, Anna F.,Paloyan, Ani M.,Panosyan, Henrik A.,Poghosyan, Artavazd S.,Saghyan, Ashot S.,Sahakyan, Lusine Yu.,Sargsyan, Armen S.,Tovmasyan, Anna S.,Tsaturyan, Avetis H.
(2020/02/18)

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)

A dynamic combinatorial library for biomimetic recognition of dipeptides in water
Small peptides are involved in countless biological processes. Hence selective binding motifs for peptides can be powerful tools for labeling or inhibition. Finding those binding motifs, especially in water which competes for intermolecular H-bonds, poses an enormous challenge. A dynamic combinatorial library can be a powerful method to overcome this issue. We previously reported artificial receptors emerging form a dynamic combinatorial library of peptide building blocks. In this study we aimed to broaden this scope towards recognition of small peptides. Employing CXC peptide building blocks, we found that cyclic dimers of oxidized CFC bind to the aromatic peptides FF and YY (K ≈ 229-702 M-1), while AA binds significantly weaker (K ≈ 65-71 M-1).
Klepel, Florian,Ravoo, Bart Jan
supporting information
p. 1588 - 1595
(2020/09/16)

"Fishing and hunting"-selective immobilization of a recombinant phenylalanine ammonia-lyase from fermentation media
This article overviews the numerous immobilization methods available for various biocatalysts such as whole-cells, cell fragments, lysates or enzymes which do not require preliminary enzyme purification and introduces an advanced approach avoiding the costly and time consuming downstream processes required by immobilization of purified enzyme-based biocatalysts (such as enzyme purification by chromatographic methods and dialysis). Our approach is based on silica shell coated magnetic nanoparticles as solid carriers decorated with mixed functions having either coordinative binding ability (a metal ion complexed by a chelator anchored to the surface) or covalent bond-forming ability (an epoxide attached to the surface via a proper linker) enabling a single operation enrichment and immobilization of a recombinant phenylalanine ammonia-lyase from parsley fused to a polyhistidine affinity tag.
Sánta-Bell, Evelin,Molnár, Zsófia,Varga, Andrea,Nagy, Flóra,Hornyánszky, Gábor,Paizs, Csaba,Balogh-Weiser, Diána,Poppe, László
supporting information

(2019/11/28)

Paired Electrochemical Reactions and the On-Site Generation of a Chemical Reagent
While the majority of reported paired electrochemical reactions involve carefully matched cathodic and anodic reactions, the precise matching of half reactions in an electrolysis cell is not generally necessary. During a constant current electrolysis almost any oxidation and reduction reaction can be paired, and in the presented work we capitalize on this observation by examining the coupling of anodic oxidation reactions with the production of hydrogen gas for use as a reagent in remote, Pd-catalyzed hydrogenation and hydrogenolysis reactions. To this end, an alcohol oxidation, an oxidative condensation, intramolecular anodic olefin coupling reactions, an amide oxidation, and a mediated oxidation were all shown to be compatible with the generation and use of hydrogen gas at the cathode. This pairing of an electrolysis reaction with the production of a chemical reagent or substrate has the potential to greatly expand the use of more energy efficient paired electrochemical reactions.
Wu, Tiandi,Nguyen, Bichlien H.,Daugherty, Michael C.,Moeller, Kevin D.
supporting information
p. 3562 - 3565
(2019/02/20)

Easy-handling and low-leaching heterogeneous palladium and platinum catalysts via coating with a silicone elastomer
We have developed a practical protocol for coating of commercial Pd/Al2O3 and Pt/Al2O3 catalysts in micro-powders with a silicone elastomer. Compared to original catalysts, the treated catalysts are easier to weight and transfer, and they are easier to recover by simple filtration. More importantly, the metal leaching of treated catalysts was significantly reduced. The treated catalysts worked very well in diverse hydrogenation reactions.
Zhou, Mi,Li, Tingting,Xu, Bo
supporting information
p. 948 - 952
(2019/03/08)

Supported Catalytically Active Supramolecular Hydrogels for Continuous Flow Chemistry
Inspired by biology, one current goal in supramolecular chemistry is to control the emergence of new functionalities arising from the self-assembly of molecules. In particular, some peptides can self-assemble and generate exceptionally catalytically active fibrous networks able to underpin hydrogels. Unfortunately, the mechanical fragility of these materials is incompatible with process developments, relaying this exciting field to academic curiosity. Here, we show that this drawback can be circumvented by enzyme-assisted self-assembly of peptides initiated at the walls of a supporting porous material. We applied this strategy to grow an esterase-like catalytically active supramolecular hydrogel (CASH) in an open-cell polymer foam, filling the whole interior space. Our supported CASH material is highly efficient towards inactivated esters and enables the kinetic resolution of racemates. This hybrid material is robust enough to be used in continuous flow reactors, and is reusable and stable over months.
Rodon Fores, Jennifer,Criado-Gonzalez, Miryam,Chaumont, Alain,Carvalho, Alain,Blanck, Christian,Schmutz, Marc,Serra, Christophe A.,Boulmedais,Schaaf, Pierre,Jierry, Lo?c
supporting information
p. 18817 - 18822
(2019/11/16)

Chemoenzymatic synthesis of L-3,4-dimethoxyphenyl-alanine and its analogues using aspartate aminotransferase as a key catalyst
In this study, a chemoenzymatic synthesis method for the production of L-3,4-dimethoxyphenyl-alanine and its analogues from phenylpyruvate derivatives was developed. The aspartate aminotransferase from Escherichia coli was engineered by error prone PCR and the improved variants were identified. When 3, 4-dimethoxy phenylpyruvate was added by fed-batch on a preparative scale, L-3,4-dimethoxyphenyl-alanine was formed in 95.4% conversion and > 99% ee with the best aspartate aminotransferase variant as the catalyst. This study provided an efficient method for the production of methoxy substituted phenylalanines using the engineered aspartate aminotransferase.
Yu, Jinhai,Li, Jing,Cao, Shuangyan,Wu, Ting,Zeng, Shuiyun,Zhang, Hongjuan,Liu, Junzhong,Jiao, Qingcai
p. 28 - 32
(2018/11/26)

An Ugi-like Biosynthetic Pathway Encodes Bombesin Receptor Subtype-3 Agonists
Isocyanide functional groups can be found in a variety of natural products. Rhabduscin is one such isocyanide-functionalized immunosuppressant produced in Xenorhabdus and Photorhabdus gammaproteobacterial pathogens, and deletion of its biosynthetic gene cluster inhibits virulence in an invertebrate animal infection model. Here, we characterized the first "opine-glycopeptide" class of natural products termed rhabdoplanins, and strikingly, these molecules are spontaneously produced from rhabduscin via an unprecedented multicomponent "Ugi-like" reaction sequence in nature. The rhabdoplanins also represent new lead G protein-coupled receptor (GPCR) agonists, stimulating the bombesin receptor subtype-3 (BB3) GPCR.
Oh, Joonseok,Kim, Nam Y.,Chen, Haiwei,Palm, Noah W.,Crawford, Jason M.
p. 16271 - 16278
(2019/11/02)

Preparation and characterization of a new open-tubular capillary column for enantioseparation by capillary electrochromatography
In order to use the enantioseparation capability of cationic cyclodextrin and to combine the advantages of capillary electrochromatography (CEC) with open-tubular (OT) column, in this study, a new OT-CEC, coated with cationic cyclodextrin (1-allylimidazolium-β-cyclodextrin [AI-β-CD]) as chiral stationary phase (CSP), was prepared and applied for enantioseparation. Synthesized AI-β-CD was characterized by infrared (IR) spectrometry and mass spectrometry (MS). The preparation conditions for the AI-β-CD-coated column were optimized with the orthogonal experiment design L9(34). The column prepared was characterized by scanning electron microscopy (SEM) and elemental analysis (EA). The results showed that the thickness of stationary phase in the inner surface of the AI-β-CD-coated columns was about 0.2 to 0.5?μm. The AI-β-CD content in stationary phase based on the EA was approximately 2.77?mmol·m?2. The AI-β-CD-coated columns could separate all 14 chiral compounds (histidine, lysine, arginine, glutamate, aspartic acid, cysteine, serine, valine, isoleucine, phenylalanine, salbutamol, atenolol, ibuprofen, and napropamide) successfully in the study and exhibit excellent reproducibility and stability. We propose that the column, coated with AI-β-CD, has a great potential for enantioseparation in OT-CEC.
Li, Yingjie,Tang, Yimin,Qin, Shili,Li, Xue,Dai, Qiang,Gao, Lidi
p. 283 - 292
(2019/02/05)

Biphasic Enantioselective Fluorescent Recognition of Amino Acids by a Fluorophilic Probe
A fluorophilic fluorescent probe based on a perfluoroalkyl-substituted bis(binaphthyl) compound was designed and synthesized. It displayed a highly enantioselective fluorescence response toward structurally diverse amino acids in a biphasic fluorous/aqueous system with enantiomeric fluorescent enhancement ratio (ef; ΔID/ΔIL) values up to 45.2 (histidine). It can be used to determine the enantiomeric compositions of amino acids and also allows the amino acid enantiomers to be visually discriminated. NMR and mass-spectroscopic investigations provided insights into the observed high enantioselectivity. This biphasic fluorescent recognition was used to determine the enantiomeric composition of the crude phenylalanine products generated by an enzyme-catalyzed asymmetric hydrolysis under various reaction conditions. The fluorous-phase-based fluorescence measurement under the biphasic conditions was able to minimize the interference of other reaction components and thus has potential in asymmetric reaction screening.
Zhu, Yuan-Yuan,Wu, Xue-Dan,Abed, Mehdi,Gu, Shuang-Xi,Pu, Lin
p. 7866 - 7873
(2019/05/10)

Preparative Asymmetric Synthesis of Canonical and Non-canonical α-amino Acids Through Formal Enantioselective Biocatalytic Amination of Carboxylic Acids
Chemical and biocatalytic synthesis of non-canonical α-amino acids (ncAAs) from renewable feedstocks and using mild reaction conditions has not efficiently been solved. Here, we show the development of a three-step, scalable and modular one-pot biocascade for linear conversion of renewable fatty acids (FAs) into enantiopure l-α-amino acids. In module 1, selective α-hydroxylation of FAs is catalyzed by the P450 peroxygenase P450CLA. By using an automated H2O2 supplementation system, efficient conversion (46 to >99%; TTN>3300) of a broad range of FAs (C6:0 to C16:0) into valuable α-hydroxy acids (α-HAs; >90% α-selective) is shown on preparative scale (up to 2.3 g L?1 isolated product). In module 2, a redox-neutral hydrogen borrowing cascade (alcohol dehydrogenase/amino acid dehydrogenase) allowed further conversion of α-HAs into l-α-AAs (20 to 99%). Enantiopure l-α-AAs (e.e. >99%) including the pharma synthon l-homo-phenylalanine can be obtained at product titers of up to 2.5 g L?1. Based on renewables and excellent atom economy, this biocascade is among the shortest and greenest synthetic routes to structurally diverse and industrially relevant ncAAs. (Figure presented.).
Dennig, Alexander,Blaschke, Fabio,Gandomkar, Somayyeh,Tassano, Erika,Nidetzky, Bernd
supporting information

(2019/02/09)

Preparative Asymmetric Synthesis of Canonical and Non-canonical a-amino Acids through Formal Enantioselective Biocatalytic Amination of Carboxylic Acids
Chemical and biocatalytic synthesis of non-canonical a-amino acids (ncAAs) from renewable feedstocks and using mild reaction conditions has not efficiently been solved. Here, we show the development of a three-step, scalable and modular one-pot biocascade for linear conversion of renewable fatty acids (FAs) into enantiopure l-a-amino acids. In module 1, selective a-hydroxylation of FAs is catalyzed by the P450 peroxygenase P450CLA. By using an automated H2O2 supplementation system, efficient conversion (46 to >99%; TTN>3300) of a broad range of FAs (C6:0 to C16:0) into valuable a-hydroxy acids (a-HAs; >90% a-selective) is shown on preparative scale (up to 2.3 gL1 isolated product). In module 2, a redox-neutral hydrogen borrowing cascade (alcohol dehydrogenase/amino acid dehydrogenase) allowed further conversion of a-HAs into l-a-AAs (20 to 99%). Enantiopure l-a-AAs (e.e. >99%) including the pharma synthon l-homo-phenylalanine can be obtained at product titers of up to 2.5 gL1. Based on renewables and excellent atom economy, this biocascade is among the shortest and greenest synthetic routes to structurally diverse and industrially relevant ncAAs.
Dennig, Alexander,Blaschke, Fabio,Gandomkar, Somayyeh,Tassano, Erika,Nidetzky, Bernd
supporting information
p. 1348 - 1358
(2019/10/28)

Recyclable and Stable α-Methylproline-Derived Chiral Ligands for the Chemical Dynamic Kinetic Resolution of free C,N-Unprotected α-Amino Acids
A novel special designed, stable, and recyclable chiral ligand bearing a quaternary carbon was developed for chemical dynamic kinetic resolution (DKR) of free C,N-unprotected racemic α-amino acids via Schiff base intermediates. This method furnishes high yields with excellent enantioselectivity, has a broad substrate scope, and uses operationally simple and convenient conditions. The present chemical DKR is a practical and useful method for the preparation of enantiopure α-amino acids.
Shu, Shuangjie,Zhao, Liang,Zhou, Shengbin,Wu, Chenglin,Liu, Hong,Wang, Jiang
(2019/06/20)

Cyclic tetrapeptides from the marine strain Streptomyces sp. PNM-161a with activity against rice and yam phytopathogens
Two cyclotetrapeptides, henceforth named Provipeptides A (1) and B (2), along with five known diketopiperazines (3–7) were isolated from the liquid culture of marine Streptomyces sp. 161a recovered from a sample of sea grass Bryopsis sp. The structures of cyclotetrapeptides and diketopiperazines (DKPs) were established by 1D and 2D NMR data, MS, and by comparison with literature data. The absolute stereochemistry of compounds cyclo-(l-Pro-l-Leu-d-Pro-l-Phe) 1 and cyclo-(-Pro-Ile-Pro-Phe) 2 was established by the Marfey’s method. Compound 1 showed antibacterial activity against rice phytopathogenic strains Burkholderia glumae (MIC = 1.1 mM) and Burkholderia gladioli (MIC = 0.068 mM), compound 2 was active only against B. glumae (MIC = 1.1 mM), and DKP cyclo-[l-Pro-l-Leu] 5 showed to be active against B. gladioli (MIC = 0.3 mM) and B. glumae (MIC = 2.4 mM). Compounds 1 and 2 showed 65% and 50% inhibition of Colletotrichum gloeosporioides (yam pathogen) conidia germination, respectively at a concentration of 1.1 mM.
Betancur, Luz A.,Forero, Abel M.,Romero-Otero, Adriana,Sepúlveda, Lady Yohanna,Moreno-Sarmiento, Nubia C.,Castellanos, Leonardo,Ramos, Freddy A.
p. 744 - 751
(2019/07/05)

Natural Hydroxamate-Containing Siderophore Acremonpeptides A-D and an Aluminum Complex of Acremonpeptide D from the Marine-Derived Acremonium persicinum SCSIO 115
Four new hydroxamate-containing natural product cyclopeptides designated acremonpeptides A-D (1-4), together with Al(III)-acremonpeptide D (5) were obtained from the marine fungus Acremonium persicinum SCSIO 115. The planar structures of 1-5 were established on the basis of HRMS as well as 1D and 2D NMR data sets. Moreover, the amino acid absolute configurations were determined using Marfey's method. Compounds 1-5 all feature three 2-amino-5-(N-hydroxyacetamido)pentanoic acid (N5-hydroxy-N5-acetyl-l-ornithine) metal ion chelating moieties. Beyond their discovery and structure elucidation, in vitro bioassays revealed acremonpeptides A (1), B (2), and Al(III)-acremonpeptide D (5) as moderate antiviral agents for herpes simplex virus 1 with EC50 values of 16, 8.7, and 14 μM, respectively.
Chen, Ziming,Huang, Hongbo,Ju, Jianhua,Luo, Minghe,Song, Xiaoxian,Wang, Xin,Zang, Ruochen
p. 2594 - 2600
(2019/10/11)

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)

Kyanamide, a new Ahp-containing depsipeptide from marine cyanobacterium Caldora penicillata
Kyanamide (1), a new depsipeptide containing 3-amino-6-hydroxy-2-piperidone moiety, was isolated from the Caldora penicillata marine cyanobacterium collected in Okinawa. Its structure was determined by spectroscopic analysis and Marfey's analysis of acid hydrolysate. Kyanamide exhibited moderate cytotoxicity against HeLa S3 cells. 1 also exhibited potent protease inhibitory activity against elastase and chymotrypsin with IC50 values of 0.13 nM and 1.1 μM.
Ozaki, Kaori,Iwasaki, Arihiro,Suenaga, Kiyotake,Teruya, Toshiaki
p. 3382 - 3386
(2019/05/15)

Microbial degradation of amino acid-containing compounds using the microcystin-degrading bacterial strain B-9
Strain B-9, which has a 99% similarity to Sphingosinicella microcystinivorans strain Y2, is a Gram-negative bacterium with potential for use in the degradation of microcystin-related compounds and nodularin. We attempted to extend the application area of strain B-9 and applied it to mycotoxins produced by fungi. Among the tested mycotoxins, only ochratoxin A was completely hydrolyzed to provide the constituents ochratoxin α and L-phenylalanine, and levels of fumonisin B1 gradually decreased after 96 h. However, although drugs including antibiotics released into the aquatic environment were applied for microbial degradation using strain B-9, no degradation occurred. These results suggest that strain B-9 can only degrade amino acid-containing compounds. As expected, the tested compounds with amide and ester bonds, such as 3,4-dimethyl hippuric acid and 4-benzyl aspartate, were readily hydrolyzed by strain B-9, although the sulfonamides remained unchanged. The ester compounds were characteristically and rapidly hydrolyzed as soon as they came into contact with strain B-9. Furthermore, the degradation of amide and ester compounds with amino acids was not inhibited by the addition of ethylenediaminetetraacetic acid (EDTA), indicating that the responsible enzyme was not MlrC. These results suggest that strain B-9 possesses an additional hydrolytic enzyme that should be designated as MlrE, as well as an esterase.
Jin, Haiyan,Hiraoka, Yoshiko,Okuma, Yurie,Hashimoto, Elisabete Hiromi,Kurita, Miki,Anas, Andrea Roxanne J.,Uemura, Hitoshi,Tsuji, Kiyomi,Harada, Ken-Ichi
(2018/02/14)

Molecularly imprinted polymer as stationary phase for HPLC separation of phenylalanine enantiomers
Abstract: l-Phenylalanine molecularly imprinted polymers were synthesized by bulk polymerization. Methacrylic acid and acrylamide were tested as functional monomers. Ethanol and acetonitrile were used as porogenic solvents. Optimal composition of polymerization mixture was methacrylic acid, template, and ethylene glycol dimethacrylate in molar ratio 1:5:26. MIP was applied as HPLC chiral stationary phase. The influences of the mobile phase composition, flow rate, column temperature, and column length on the efficiency of enantioseparation were investigated. The enantioselective separation of phenylalanine was attained in reversed phase mode at 45?°C with acetonitrile/water containing 1.5% acetic acid (90/10, v/v) as mobile phase (resolution value was 1.49, selectivity factor was 1.38). Applicability of polymeric stationary phase prepared for l-phenylalanine was tested for analysis of dietary supplement sample. The UV detection limits for both enantiomers were 1?mg?cm?3 (S/N?=?3). Good linearity was observed from 1 to 10?mg?cm?3.
Hroboňová, Katarína,Lomenova, Anna
p. 939 - 946
(2018/02/21)

Evaluation of the Edman degradation product of vancomycin bonded to core-shell particles as a new HPLC chiral stationary phase
A modified macrocyclic glycopeptide-based chiral stationary phase (CSP), prepared via Edman degradation of vancomycin, was evaluated as a chiral selector for the first time. Its applicability was compared with other macrocyclic glycopeptide-based CSPs: TeicoShell and VancoShell. In addition, another modified macrocyclic glycopeptide-based CSP, NicoShell, was further examined. Initial evaluation was focused on the complementary behavior with these glycopeptides. A screening procedure was used based on previous work for the enantiomeric separation of 50 chiral compounds including amino acids, pesticides, stimulants, and a variety of pharmaceuticals. Fast and efficient chiral separations resulted by using superficially porous (core-shell) particle supports. Overall, the vancomycin Edman degradation product (EDP) resembled TeicoShell with high enantioselectivity for acidic compounds in the polar ionic mode. The simultaneous enantiomeric separation of 5 racemic profens using liquid chromatography-mass spectrometry with EDP was performed in approximately 3?minutes. Other highlights include simultaneous liquid chromatography separations of rac-amphetamine and rac-methamphetamine with VancoShell, rac-pseudoephedrine and rac-ephedrine with NicoShell, and rac-dichlorprop and rac-haloxyfop with TeicoShell.
Hellinghausen, Garrett,Lopez, Diego A.,Lee, Jauh T.,Wang, Yadi,Weatherly, Choyce A.,Portillo, Abiud E.,Berthod, Alain,Armstrong, Daniel W.
p. 1067 - 1078
(2018/08/01)

Complex-precipitation using functionalized chiral ionic liquids with L-proline anion and chromatographic analysis for enantioseparation of racemic amino acids
As one kind of functionalized green medium, chiral ionic liquids (CILs) have been widely applied in fields of asymmetric catalysis, enantioseparation, and so on. In this study, four kinds of amino acid–based CILs were synthesized by using trimethylamine, N-methylpyrrolidine, N-methylimidazole, and tropine as cationic nucleus, respectively. Then their specific optical rotation and solubility in common solvents were determined for further resolution application. The effect of different cations in these CILs was explored on the separation of racemic phenylalanine in complex-precipitation way. Moreover, various factors were systematically investigated for their effects on resolution efficiency, including the type of additive copper salts, the molar ratio of Cu (II) to CIL, pH value, the amount of racemic phenylalanine, and temperature. Under the appropriate conditions, L-phenylalanine mainly existed in solid phase and could be separated from its enantiomers in liquid phase. Furthermore, the mechanism of resolution was studied by thermogravimetric analysis, infrared spectrum, and molecular simulation. The resolution system has characteristics of no organic solvent, fast separation speed, simple resolution process, and easy scale-up.
Zang, Huimin,Yao, Shun,Luo, Yingjie,Tang, Dan,Song, Hang
p. 1182 - 1194
(2018/09/12)

Accessing d-Valine Synthesis by Improved Variants of Bacterial Cyclohexylamine Oxidase
Chemoenzymatic deracemization was applied to prepare d-valine from racemic valine ethyl ester or l-valine ethyl ester in high yield (up to 95 %) with excellent optical purity (>99 % ee) by employing a newly evolved cyclohexylamine oxidase (CHAO) variant Y321I/M226T exhibiting catalytic efficiency that was 30 times higher than that of the wildtype CHAO. Interestingly, CHAO and its variants showed opposite enantioselectivity for valine ethyl ester and phenylalanine ethyl ester.
Gong, Rui,Yao, Peiyuan,Chen, Xi,Feng, Jinhui,Wu, Qiaqing,Lau, Peter C. K.,Zhu, Dunming
p. 387 - 390
(2017/12/26)

Structural Diversity and Anticancer Activity of Marine-Derived Elastase Inhibitors: Key Features and Mechanisms Mediating the Antimetastatic Effects in Invasive Breast Cancer
Three new 3-amino-6-hydroxy-2-piperidone (Ahp)-containing cyclic depsipeptides, named loggerpeptins A–C (1–3), along with molassamide (4), were discovered from a marine cyanobacterium, extending the structural diversity of this prevalent scaffold of cyanobacterial serine protease inhibitors. Molassamide, which contains a 2-amino-butenoic (Abu) unit in the cyclic core, was the most potent and selective analogue against human neutrophil elastase (HNE). Given the growing evidence supporting the role of HNE in breast cancer progression and metastasis, we assessed the cellular effects of compounds 3 and 4 in the context of targeting invasive breast cancer. Both compounds inhibited cleavage of the elastase substrate CD40 in biochemical assays; however, only 4 exhibited significant cellular activity. As CD40 and other receptor proteolytic processing culminates in NFκB activation, we assessed the effects of 4 on the expression of target genes, including ICAM-1. ICAM-1 is also a direct target of elastase and, in our studies, compound 4 attenuated both elastase-induced ICAM-1 gene expression and ICAM-1 proteolytic processing by elastase, revealing a potential dual effect on migration through modulation of gene expression and proteolytic processing. Molassamide also specifically inhibited the elastase-mediated migration of highly invasive triple-negative breast cancer cells.
Al-Awadhi, Fatma H.,Paul, Valerie J.,Luesch, Hendrik
p. 815 - 825
(2018/03/27)

Tolyprolinol, a new dipeptide from Tolypocladium sp. FKI-7981
A new dipeptide, named tolyprolinol, was isolated from the static culture of a fungus, Tolypocladium sp. FKI-7981. The structure of tolyprolinol was elucidated as N-acetyl-l-phenylalanyl-l-prolinol. It showed moderate antimalarial activity but did not show cytotoxicity or any other antimicrobial property.
Fukasawa, Wataru,Mori, Natsuki,Iwatsuki, Masato,Hokari, Rei,Ishiyama, Aki,Nakajima, Moe,Ouchi, Takahito,Nonaka, Kenichi,Kojima, Hiroki,Matsuo, Hirotaka,ōmura, Satoshi,Shiomi, Kazuro
p. 682 - 684
(2018/03/26)

An amine protecting group deprotectable under nearly neutral oxidative conditions
The 1,3-dithiane-based dM-Dmoc group was studied for the protection of amino groups. Protection was achieved under mild conditions for aliphatic amines, and under highly reactive conditions for the less reactive arylamines. Moderate to excellent yields were obtained. Deprotection was performed by oxidation followed by treating with a weak base. The yields were good to excellent. The new amino protecting group offers a different dimension of orthogonality in reference to the commonly used amino protecting groups in terms of deprotection conditions. It is expected to allow a collection of transformations to be carried out on the protected substrates that are unattainable using any known protecting groups.
Shahsavari, Shahien,McNamara, Chase,Sylvester, Mark,Bromley, Emily,Joslin, Savannah,Lu, Bao-Yuan,Fang, Shiyue
p. 1750 - 1757
(2018/08/21)

Natalenamides A–C, cyclic tripeptides from the termite-associated Actinomadura sp. RB99
In recent years, investigations into the biochemistry of insect-associated bacteria have increased. When combined with analytical dereplication processes, these studies provide a powerful strategy to identify structurally and/or biologically novel compounds. Non-ribosomally synthesized cyclic peptides have a broad bioactivity spectrum with high medicinal potential. Here, we report the discovery of three new cyclic tripeptides: natalenamides A–C (compounds 1–3). These compounds were identified from the culture broth of the fungus-growing termite-associated Actinomadura sp. RB99 using a liquid chromatography (LC)/ultraviolet (UV)/mass spectrometry (MS)-based dereplication method. Chemical structures of the new compounds (1–3) were established by analysis of comprehensive spectroscopic methods, including one-dimensional (1H and13C) and two-dimensional (1H-1H-COSY, HSQC, HMBC) nuclear magnetic resonance spectroscopy (NMR), together with high-resolution electrospray ionization mass spectrometry (HR-ESIMS) data. The absolute configurations of the new compounds were elucidated using Marfey’s analysis. Through several bioactivity tests for the tripeptides, we found that compound 3 exhibited significant inhibitory effects on 3-isobutyl-1-methylxanthine (IBMX)-induced melanin production. The effect of compound 3 was similar to that of kojic acid, a compound extensively used as a cosmetic material with a skin-whitening effect.
Lee, Seoung Rak,Lee, Dahae,Yu, Jae Sik,Benndorf, René,Lee, Sullim,Lee, Dong-Soo,Huh, Jungmoo,Wilhelm de Beer,Kim, Yong Ho,Beemelmanns, Christine,Kang, Ki Sung,Kim, Ki Hyun
(2018/11/24)

Colony-wise Analysis of a Theonella swinhoei Marine Sponge with a Yellow Interior Permitted the Isolation of Theonellamide i
There are several examples of marine organisms whose metabolic profiles differ among conspecifics inhabiting the same region. We have analyzed the metabolic profile of each colony of a Theonella swinhoei marine sponge with a yellow interior and noticed the patchy distribution of one metabolite. This compound was isolated and its structure was studied by a combination of spectrometric analyses and chemical degradation, showing it to be a congener in the theonellamide class of bicyclic peptides. Theonellamides had previously been isolated by us only from T. swinhoei with a white interior and not from those with a yellow interior.
Fukuhara, Kazuya,Takada, Kentaro,Watanabe, Ryuichi,Suzuki, Toshiyuki,Okada, Shigeru,Matsunaga, Shigeki
p. 2595 - 2599
(2018/12/13)

Croissamide, a proline-rich cyclic peptide with an N-prenylated tryptophan from a marine cyanobacterium Symploca sp.
Croissamide, a proline-rich cyclic peptide that contains an N-prenylated tryptophan, was isolated from a marine cyanobacterium Symploca sp. Its gross structure was determined by spectroscopic analyses, and the absolute configuration was established based on chiral HPLC analyses of acid hydrolysates.
Iwasaki, Keitaro,Iwasaki, Arihiro,Sumimoto, Shimpei,Sano, Takuya,Hitomi, Yuki,Ohno, Osamu,Suenaga, Kiyotake
supporting information
p. 3806 - 3809
(2018/09/17)

Reversible Folding of a β-Hairpin Peptide by a Metal-Chelating Amino Acid
5-(1-Hydroxy-pyridin-2(1H)-onyl)-l-alanine (Hop) is a N-hydroxy-1,2-pyridone functionalized α-amino acid with the desired metal-chelating properties of DOPA (3,4-dihydroxy phenylalanine) but without its unwanted redox activity. The Fmoc-protected amino acid Fmoc-l-Hop(tBu)-OH (11) was synthesized from glycine phosphonate followed by enzymatic hydrolysis of the methyl ester yielding the Hop l-isomer in 96 % ee. The amino acid 11 is used in automated peptide synthesis for the assembly of a 14mer β-hairpin peptide with the sequence [dsb1, 14]H-CHXETGKHGHKLVC-OH (X=W, l-Hop). While the 10 π electron containing indole side chain of l-Trp in peptide 14 completes the formation of a hydrophobic cluster and results in 90 % folding, the folded fraction is significantly decreased to approximately 30 % for the 6 π electron l-Hop side chain in peptide 16. Metal chelation of Ga3+ reconstitutes the folding of 16 to above 60 % due to the formation of the Ga(16)3 trimer. The chelation process of 16 is monitored by NMR spectroscopy and the subsequent release of Ga3+ by a competitive metal chelator exemplifies the reversible oligomerization of peptide epitopes by metal chelation, bearing the opportunity to synthesize protein-sized aggregates on the basis of reversible chemistry in water.
Reutzel, Jan,Diogo, Timm M.,Geyer, Armin
supporting information
p. 8450 - 8456
(2017/06/28)

Bio-inspired enantioselective full transamination using readily available cyclodextrin
The mimics of vitamin B6-dependent enzymes that catalyzed an enantioselective full transamination in the pure aqueous phase have been realized for the first time through the establishment of a new “pyridoxal 5′-phosphate (PLP) catalyzed non-covalent cyclodextrin (CD)-keto acid inclusion complexes” system, and various optically active amino acids have been obtained.
Zhang, Shiqi,Li, Guangxun,Liu, Hongxin,Wang, Yingwei,Cao, Yuan,Zhao, Gang,Tang, Zhuo
p. 4203 - 4208
(2017/02/05)

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)