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Noncovalently Functionalized Commodity Polymers as Tailor-Made Additives for Stereoselective Crystallization
Stereoselective inhibition of the nucleation and crystal growth of one enantiomer aided by “tailor-made” polymeric additives is an efficient method to obtain enantiopure compounds. However, the conventional preparation of polymeric additives from chiral monomers are laborious and limited in structures, which impedes their rapid optimization and applicability. Herein, we report a “plug-and-play” strategy to facilitate synthesis by using commercially available achiral polymers as the platform to attach various chiral small molecules as the recognition side-chains through non-covalent interactions. A library of supramolecular polymers made up of two vinyl polymers and six small molecules were applied with seeds in the selective crystallization of seven racemates in different solvents. They showed good to excellent stereoselectivity in yielding crystals with high enantiomeric purities in conglomerates and racemic compound forming systems. This convenient, low-cost modular synthesis strategy of polymeric additives will allow for high-efficient, economical resolution of various racemates on different scales.
Wan, Xinhua,Wang, Zhaoxu,Ye, Xichong,Zhang, Jie
supporting information
p. 20243 - 20248
(2021/08/09)

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 method of synthesizing L - asparagine (by machine translation)
The invention provides a method of synthesizing L - asparagine, the main technical means is to L - aspartic acid as the raw material, first to the reaction in the cauldron the pump enters methanol, then open the reaction kettle, input L - aspartic acid, cooling, subsequently drop adds the chlorination sulfoxide, generating L - aspartic acid methyl ester hydrochloride, then will be of the L - aspartic acid methyl ester hydrochloride into a reaction kettle, then to the reaction in the cauldron the pump enters the ammonia, to obtain the L - asparagine, the method generating L - aspartic acid methyl ester hydrochloride intermediate product, the intermediate product is stable structure, safe and non-toxic, for subsequent operation processing, reaction process only needs to have the participation of ammonia water, reactant complex, the small influence of the product, the method of the invention recovery of the methanol up to 99.5 - 99.9%, not only improving the intermediate the purity of the product, and also avoids the pollution of methanol, L - asparagine is finished effective content of 80 - 85%, moisture content is 15 - 18%, yield and moisture content are higher than the amount of the existing products, the method of the invention is suitable for industrial production. (by machine translation)
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(2019/05/08)

Self-Reporting Inhibitors: A Single Crystallization Process To Obtain Two Optically Pure Enantiomers
Collection of two optically pure enantiomers in a single crystallization process can significantly increase the chiral separation efficiency but this is difficult to realize. Now a self-reporting strategy is presented for visualizing the crystallization process by a dyed self-assembled inhibitor made from the copolymers with tri(ethylene glycol)-grafting polymethylsiloxane as the main chain and poly(N6-methacryloyl-l-lysine) as side chains. When applied with seeds together for the fractional crystallization of conglomerates, the inhibitors can label the formation of the secondary crystals and guide the complete separation process of two enantiomers with colorless crystals as the first product and red crystals as the second. This method leads to high optical purity of d/l-Asn?H2O (99.9 % ee for d-crystals and 99.5 % for l-crystals) in a single crystallization process. It requires a small amount of additives and shows excellent recyclability.
Ye, Xichong,Cui, Jiaxi,Li, Bowen,Li, Na,Zhang, Jie,Wan, Xinhua
p. 8120 - 8124
(2018/06/29)

β-Cyclodextrin Functionalized Nanoporous Graphene Oxides for Efficient Resolution of Asparagine Enantiomers
Efficient resolution of racemic mixture has long been an attractive but challenging subject since Pasteur separated tartrate enantiomers in 19th century. Graphene oxide (GO) could be flexibly functionalized by using a variety of chiral host molecules and therefore, was expected to show excellent enantioselective resolution performance. However, this combination with efficient enantioselective resolution capability has been scarcely demonstrated. Here, nanoporous graphene oxides were produced and then covalently functionalized by using a chiral host material-β-cyclodextrin (β-CD). This chiral GO displayed enantioselective affinity toward the l-enantiomers of amino acids. In particular, >99 % of l-asparagine (Asn) was captured in a racemic solution of Asn while the adsorption of d-enantiomer was not observed. This remarkable resolution performance was subsequently modelled by using an attach-pull-release dynamic method. We expect this preliminary concept could be expanded to other chiral host molecules and be employed to current membrane separation technologies and finally show practical use for many other racemates.
Qie, Fengxiang,Guo, Jiahui,Tu, Bin,Zhao, Xing,Zhang, Yuchun,Yan, Yong
supporting information
p. 2812 - 2817
(2018/09/12)

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)

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)

Influence of the amino acid side chain on peptide bond hydrolysis catalyzed by a dimeric Zr(iv)-substituted Keggin type polyoxometalate
Peptide bond hydrolysis of 18 different dipeptides, divided into four groups depending on the nature of the amino acid side chain, by the dimeric Zr(iv)-substituted Keggin type polyoxometalate (POM) (Et2NH2)8[{α-PW11O39Zr-(μ-OH)(H2O)}2]·7H2O (1) was studied by means of kinetic experiments and 1H/13C NMR spectroscopy. The observed rate constants highly depend on the bulkiness and chemical nature of the X amino acid side chain. X-Ser and X-Thr dipeptides showed increased reactivity due to intramolecular nucleophilic attack of the hydroxyl group in the side chain on the amide carbon, resulting in a reactive ester intermediate. A similar effect in which the amino acid side chain acted as an internal nucleophile was observed for the hydrolysis of Gly-Asp. Interestingly, in the presence of 1 deamidation of Gly-Asn and Gly-Gln into Gly-Asp and Gly-Glu was observed. Dipeptides containing positively charged amino acid side chains were hydrolyzed at higher rates due to electrostatic interactions between the negatively charged POM surface and positive amino acid side chains.
Ly, Hong Giang T.,Absillis, Gregory,Parac-Vogt, Tatjana N.
p. 976 - 984
(2016/02/19)

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)

Microseiramide from the freshwater cyanobacterium Microseira sp. UIC 10445
Abstract Microseiramide (1), a cyclic heptapeptide, was isolated from a sample of the freshwater cyanobacterium Microseira sp. UIC 10445 collected in a shallow lake in Northern Indiana. Taxonomic identification of UIC 10445 was performed by a combination of morphological and phylogenetic characterization. Phylogenetic analysis revealed that UIC 10445 was a member of the recently described genus Microseira, which is phylogenetically distinct from the morphologically similar genera, Moorea and Lyngbya. The planar structure of microseiramide (1) was determined by extensive 1D and 2D NMR experiments as well as HRESIMS analysis. The absolute configurations of amino acid residues were determined using acid hydrolysis followed by the advanced Marfey's analysis. Microseiramide (1) is the first cyclic peptide reported from a Microseira sp., and the structure of microseiramide (1) is distinct from the previously known metabolites from cyanobacteria of the genera Moorea and Lyngbya.
Luo, Shangwen,Krunic, Aleksej,Chlipala, George E.,Orjala, Jimmy
p. 47 - 52
(2015/06/08)

Facile synthesis of α-hydroxy carboxylic acids from the corresponding α-amino acids
An effective and improved procedure is developed for the synthesis of α-hydroxy carboxylic acids by treatment of the corresponding protonated α-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located α to a carboxylic acid function in order to undergo initial diazotization and successive hydroxylation, since neither β-amino acids nor acid derivatives such as esters and amides undergo hydroxylations. The method is successfully applied for the synthesis of 18 proteinogenic amino acids.
Stuhr-Hansen, Nicolai,Padrah, Shahrokh,Str?mgaard, Kristian
supporting information
p. 4149 - 4151
(2015/02/02)

A mild removal of Fmoc group using sodium azide
A mild method for effectively removing the fluorenylmethoxycarbonyl (Fmoc) group using sodium azide was developed. Without base, sodium azide completely deprotected Nα-Fmoc-amino acids in hours. The solvent-dependent conditions were carefully studied and then optimized by screening different sodium azide amounts and reaction temperatures. A variety of Fmoc-protected amino acids containing residues masked with different protecting groups were efficiently and selectively deprotected by the optimized reaction. Finally, a biologically significant hexapeptide, angiotensin IV, was successfully synthesized by solid phase peptide synthesis using the developed sodium azide method for all Fmoc removals. The base-free condition provides a complement method for Fmoc deprotection in peptide chemistry and modern organic synthesis. Graphical Abstract: [Figure not available: see fulltext.]
Chen, Chun-Chi,Rajagopal, Basker,Liu, Xuan Yu,Chen, Kuan Lin,Tyan, Yu-Chang,Lin, Fui,Lin, Po-Chiao
p. 367 - 374
(2014/03/21)

Chemical evolution of simple amino acids to asparagine under discharge onto the primitive hydrosphere: Simulation experiments using contact glow discharge
Asparagine is an important amino acid for abiotic polypeptide synthesis. In simulation experiments, it was obtained in 3.0% yield (based on the amount of consumed alanine) from alanine (100 mM) and formamide (200 mM) by contact glow discharge (Harada discharge) onto aqueous solutions. The present results suggest that asparagine could be abiotically synthesized from simple amino acids under possible primitive earth conditions.
Munegumi, Toratane
p. 1208 - 1215
(2015/02/19)

Cystomanamides: Structure and biosynthetic pathway of a family of glycosylated lipopeptides from myxobacteria
Cystomanamides A-D were isolated as novel natural product scaffolds from Cystobacter fuscus MCy9118, and their structures were established by spectroscopic techniques including 2D NMR, LC-SPE-NMR/-MS, and HR-MS. The cystomanamides contain β-hydroxy amino acids along with 3-amino-9-methyldecanoic acid that is N-glycosylated in cystomanamide C and D. The gene cluster for cystomanamide biosynthesis was identified by gene disruption as PKS/NRPS hybrid incorporating an iso-fatty acid as starter unit and including a reductive amination step at the interface of the PKS and NRPS modules.
Etzbach, Lena,Plaza, Alberto,Garcia, Ronald,Baumann, Sascha,Mueller, Rolf
supporting information
p. 2414 - 2417
(2014/05/20)

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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(2015/01/07)

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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(2013/08/15)

Microbial enantioselective removal of the N-benzyloxycarbonyl amino protecting group
In order to deprotect N-carbobenzoxy-l-aminoacids (Cbz-AA) and related compounds, a series of microorganisms was selected from soil by enrichment cultures with Cbz-l-Glu as sole nitrogen source. A lyophilized whole-cell preparation of two Arthrobacter sp. strains grown on Cbz-Glu or Cbz-Gly exhibited a high cleavage activity. The conditions of hydrolysis have been optimized and a quantitative enantioselective deprotection of several Cbz-dl-amino acids was obtained, as well as the deprotection of N-carbamoylester derivatives of several synthetic amino compounds. The preparation of Cbz-d-allylglycine and l-allylglycine in high yield and high optical purity is described as an application of this method.
Maurs, Michele,Acher, Francine,Azerad, Robert
p. 22 - 26
(2012/10/29)

Cytotoxic cyclic depsipeptides from the Australian marine sponge Neamphius huxleyi
Three new cyclic depsipeptides, neamphamides B (2), C (3), and D (4), were isolated from the Australian sponge Neamphius huxleyi. The planar structural characterization of these molecules was elucidated using 2D NMR experiments and ESI-FTICR-MSn. Their configurations were determined by Marfey's method and J-based NMR analysis. These new metabolites inhibited the growth of human cell lines (A549, HeLa, LNCaP, PC3, and NFF) with IC50 values ranging from 88 to 370 nM. However, neamphamide D causes A549 cell proliferation at subcytotoxic doses and should be treated cautiously as a cytotoxic compound.
Tran, Trong D.,Pham, Ngoc B.,Fechner, Gregory,Zencak, Dusan,Vu, Hoan T.,Hooper, John N.A.,Quinn, Ronald J.
p. 2200 - 2208
(2013/02/25)

An efficient route to both enantiomers of allo-threonine by simultaneous amino acid racemase-catalyzed isomerization of threonine and crystallization
We present an efficient method for the production of D- and L-allo-threonine (allo-Thr) with very high purity by enzymatic isomerization of L- or D-threonine (Thr) and simultaneous crystallization. Isomerization of Thr to allo-Thr is catalyzed by a purified amino acid racemase (AArac12996) from Pseudomonas putida NBRC12996, which can easily be obtained from a recombinant E. coli strain by secretion into the medium and subsequent anion exchange chromatography. Crystallization of D- and L-allo-Thr was performed in a repetitive batch mode over a period of up to 55 days at 30 °C. Total amounts of 30.8 g D-allo-Thr and 32.4 g L-allo-Thr were obtained with a very good diastereomeric excess of deD-allo>99.2% and de L-allo>98.4%, respectively, and in good yields (D-allo-Thr: 83%, L-allo-Thr: 79%). The enzyme's remarkable high stability under process conditions resulted in enzyme specific yields of 2.56 g D-allo-Thr per mg AArac12996 and 1.62 g L-allo-Thr per mg AArac12996. In contrast to chemical multi-step syntheses of allo-Thr, our process consists of only one enzyme-catalyzed reaction step with simultaneous product crystallization. The process is performed under low energy consumption (30 °C, atmospheric pressure) in water and avoids the use and production of any toxic or harmful compounds. Recovery of the enantiomerically pure products is performed by simple filtration which reduces downstream processing significantly compared to chromatographic methods which are usually applied. Copyright
Wuerges, Kerstin,MacKfeld, Ursula,Pohl, Martina,Luetz, Stephan,Wilhelm, Susanne,Wiechert, Wolfgang,Kubitzki, Tina
experimental part
p. 2431 - 2438
(2011/11/06)

Structure, mechanism, and substrate profile for Sco3058: The closest bacterial homologue to human renal dipeptidase
Human renal dipeptidase, an enzyme associated with glutathione metabolism and the hydrolysis of β-lactams, is similar in sequence to a cluster of ～400 microbial proteins currently annotated as nonspecific dipeptidases within the amidohydrolase superfamily. The closest homologue to the human renal dipeptidase from a fully sequenced microbe is Sco3058 from Streptomyces coelicolor. Dipeptide substrates of Sco3058 were identified by screening a comprehensive series of L-Xaa-L-Xaa, L-Xaa-D-Xaa, and D-Xaa-L-Xaa dipeptide libraries. The substrate specificity profile shows that Sco3058 hydrolyzes a broad range of dipeptides with a marked preference for an L-amino acid at the N-terminus and a D-amino acid at the C-terminus. The best substrate identified was L-Arg-D-Asp (kcat/Km = 7.6 x 105 M -1 s-1). The three-dimensional structure of Sco3058 was determined in the absence and presence of the inhibitors citrate and a phosphinate mimic of L-Ala-D-Asp. The enzyme folds as a (β/α)8 barrel, and two zinc ions are bound in the active site. Site-directed mutagenesis was used to probe the importance of specific residues that have direct interactions with the substrate analogues in the active site (Asp-22, His-150, Arg-223, and Asp-320). The solvent viscosity and kinetic effects of D2O indicate that substrate binding is relatively sticky and that proton transfers do not occurr during the rate-limiting step. A bell-shaped pH-rate profile for kcat and kcat/Km indicated that one group needs to be deprotonated and a second group must be protonated for optimal turnover. Computational docking of high-energy intermediate forms of L/D-Ala-L/D-Ala to the three-dimensional structure of Sco3058 identified the structural determinants for the stereochemical preferences for substrate binding and turnover.
Cummings, Jennifer A.,Nguyen, Tinh T.,Fedorov, Alexander A.,Kolb, Peter,Xu, Chengfu,Fedorov, Elena V.,Shoichet, Brian K.,Barondeau, David P.,Almo, Steven C.,Raushel, Frank M.
experimental part
p. 611 - 622
(2011/01/04)

A conserved glutamate controls the commitment to acyl-adenylate formation in asparagine synthetase
Inhibitor docking studies have implicated a conserved glutamate residue (Glu-348) as a general base in the synthetase active site of the enzyme asparagine synthetase B from Escherichia coli (AS-B). We now report steady-state kinetic, isotope transfer, and positional isotope exchange experiments for a series of site-directed AS-B mutants in which Glu-348 is substituted by conservative amino acid replacements. We find that formation of the β-aspartyl-AMP intermediate, and therefore the eventual production of asparagine, is dependent on the presence of a carboxylate side chain at this position in the synthetase active site. In addition, Glu-348 may also play a role in mediating the conformational changes needed to (i) coordinate, albeit weakly, the glutaminase and synthetase activities of the enzyme and (ii) establish the structural integrity of the intramolecular tunnel along which ammonia is translocated. The importance of Glu-348 in mediating acyl-adenylate formation contrasts with the functional role of the cognate residues in β-lactam synthetase (BLS) and carbapenam synthetase (CPS) (Tyr-348 and Tyr-345, respectively), which both likely evolved from asparagine synthetase. Given the similarity of the chemistry catalyzed by AS-B, BLS, and CPS, our work highlights the difficulty of predicting the functional outcome of single site mutations on enzymes that catalyze almost identical chemical transformations.
Meyer, Megan E.,Gutierrez, Jemy A.,Raushel, Frank M.,Richards, Nigel G. J.
experimental part
p. 9391 - 9401
(2011/11/28)

Purification, characterization, molecular cloning, and expression of a new aminoacylase from streptomyces mobaraensis that can hydrolyze N-(Middle/Long)-chain-fatty-acyl-L-amino acids as well as N-Short-chain-acyl-L- amino acids
We report here on the purification, characterization, molecular cloning, and expression of a new aminoacylase, initially isolated from the supernatant of Streptomyces mobaraensis (Sm-AA). Purified wild-type Sm-AA was found to be a monomeric protein with a molecular mass of 55 kDa. The cloned gene of Sm-AA contained an ORF of 1,383 bp, encoding a polypeptide of 460 amino acids. A BLAST search revealed that Sm-AA belongs to the peptidase M20 family, with identities to a hypothetical protein from Streptomyces pristinaespiralis, a putative peptidase from Streptomyces avermitilis, peptidase M20 from Frankia sp., succinyl-diaminopimelate desuccinylase from Hemophilus influenzae, and aminoacylase-1 from porcine kidney at 89, 88, 67, 29, and 25% respectively. The Sm-AA gene was subcloned into an expression vector, pSH19, and was expressed in Streptomyces lividans TK24. The amount of the recombi- nant Sm-AA expressed in the S. lividans cells was approximately 42-fold higher than that of Sm-AA found in the supernatant of S. mobaraensis. Sm-AA showed high hydrolytic activity towards various N-acetyl-L-amino acids and N-(middle/long)-chain-fatty-acyl-L- amino acids, with a preference for the acyl derivatives of L-Met, L-Ala, L-Cys, etc. with an optimum pH and temperature for reaction of about 7.5 and 50 °C (at pH 7.5).
Koreishi, Mayuko,Nakatani, Yasuyuki,Ooi, Manami,Imanaka, Hiroyuki,Imamura, Koreyoshi,Nakanishi, Kazuhiro
experimental part
p. 1940 - 1947
(2010/07/02)

Synthesis of pyrimidines and triazines in ice: Implications for the prebiotic chemistry of nucleobases
Herein, we report the efficient synthesis of RNA bases and func-tionalized s-triazines from 0.1 M urea solutions in water after subjection to freeze-thaw cycles for three weeks. The icy solution was under a reductive, methane-based atmosphere, which was s
Menor-Salvan, Cesar,Ruiz-Bermejo, Dra. Marta,Guzman, Marcelo I.,Osuna-Esteban, Susana,Veintemillas-Verdaguer, Sabino
experimental part
p. 4411 - 4418
(2009/12/07)

Cyclic depsipeptides, ichthyopeptins A and B, from Microcystis ichthyoblabe
Bioassay-guided isolation of antiviral compounds from the cultured cyanobacterium Microcystis ichthyoblabe provided two novel cyclic depsipeptides, ichthyopeptins A (1) and B (2). Their structures were determined by 1D ( 1H and 13C) and 2D (COSY, TOCSY, ROESY, HMQC, and HMBC) NMR spectra, ESIMS-MS, and amino acid analysis. The fraction containing both cyclic depsipeptides exhibited antiviral activity against influenza A virus with an IC50 value of 12.5 μg/mL.
Zainuddin, Elmi N.,Mentel, Renate,Wray, Victor,Jansen, Rolf,Nimtz, Manfred,Lalk, Michael,Mundt, Sabine
p. 1084 - 1088
(2008/02/13)

Preparation of D-amino acids by enzymatic kinetic resolution using a mutant of penicillin-G acylase from E. coli
We have demonstrated for the first time that d-glutamine (d-Gln) and d-glutamic acid (d-Glu) can be efficiently obtained in high ee (97% and 90%, respectively) by enzymatic kinetic resolution of d,l-Gln and d,l-Glu. This was achieved by enantioselective conversion of the l-enantiomers to their N-phenylacetyl derivatives in aqueous solution, using a mutant of penicillin-G acylase (PGA) from E. coli and phenylacetic acid methylester as the acyl donor. Kinetic modeling studies suggest that the high ee values obtained are both due to a strong enantiopreference for the l-amino acid in the deacylation step of the covalent enzyme intermediate, as well as to completeness of conversion that is transiently obtained as a result of the distinct preference of the mutant PGA for phenylacetic acid methylester over the N-phenylacetyl-l-amino acid product. For the other amino acids tested (Asn, Asp, and Ser), the highest ee values that were obtained for the remaining d-enantiomer are moderate (50-80%) because of lower enantioselectivity in the enzyme deacylation step and due to less complete conversion of the l-amino acid caused by competition for the active site between the acyl donor and the N-phenylacetyl-l-amino acid that is produced. The results demonstrate that the mutated PGA has great potential for the production of optically active D-amino acids by kinetic resolution.
Carboni, Chiara,Kierkels, Hans G. T.,Gardossi, Lucia,Tamiola, Kamil,Janssen, Dick B.,Quaedflieg, Peter J. L. M.
p. 245 - 251
(2007/10/03)

Kinetic mechanism of asparagine synthetase from Vibrio cholerae
Asparagine synthetase B (AsnB) catalyzes the formation of asparagine in an ATP-dependent reaction using glutamine or ammonia as a nitrogen source. To obtain a better understanding of the catalytic mechanism of this enzyme, we report the cloning, expression, and kinetic analysis of the glutamine- and ammonia-dependent activities of AsnB from Vibrio cholerae. Initial velocity, product inhibition, and dead-end inhibition studies were utilized in the construction of a model for the kinetic mechanism of the ammonia- and glutamine-dependent activities. The reaction sequence begins with the ordered addition of ATP and aspartate. Pyrophosphate is released, followed by the addition of ammonia and the release of asparagine and AMP. Glutamine is simultaneously hydrolyzed at a second site and the ammonia intermediate diffuses through an interdomain protein tunnel from the site of production to the site of utilization. The data were also consistent with the dead-end binding of asparagine to the glutamine binding site and PPi with free enzyme. The rate of hydrolysis of glutamine is largely independent of the activation of aspartate and thus the reaction rates at the two active sites are essentially uncoupled from one another.
Fresquet, Vicente,Thoden, James B.,Holden, Hazel M.,Raushel, Frank M.
p. 63 - 75
(2007/10/03)

Resolution of DL-racemic mixtures
The present invention relates to a process for the resolution of DL-racemic mixtures of compounds which crystalize in the form of a conglumerate. Both, the D and L-enantiomers are obtained according to the invention in a industrially feasable process by adding chiral enantioselective polymers to the supersaturated solution of the racemat to inhibit crystalization of one enantiomer. Next a DL-racemic mixture of said compound is suspended in about twice the amount of the crystallized enantiomer. Consequently, the opposite enantiomer could be recovered by said suspension by physical separation.
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(2008/06/13)

Monoclonal antibody against human telomerase catalytic subunit
The present invention provides a monoclonal antibody which can specifically and efficiently recognize hTERT protein; which is the catalytic subunit of telomerase, and provides a human chimeric antibody, a CDR grafted antibody, a single chain antibody, and a disulfide stabilized antibody each containing the monoclonal antibody. In addition, the present invention provides a method for detecting/quantitating hTERT protein using these antibodies, and provides diagnosis method, diagnosis agent, and therapeutic agent, for diseases, such as cancer, in which telomerase is involved using these bodies.
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(2008/06/13)

Application of 4-alkoxy-1,1,1-trifluoro[chloro]alk-3-en-2-ones as selective protecting groups of amino acids
A convenient selective protection of the α-amino carboxyl group of amino acids bearing reactive side chain groups such as arginine, asparagine, glutamine, cysteine, histidine, serine and lysine, using 4-alkoxy-1,1,1-trifluoro[chloro]alk-3-en-2-ones is reported. The reactions were performed without esterification of the carboxyl group and N-deprotection was carried out using a six molar solution of hydrochloric acid.
Zanatta, Nilo,Squizani, Adriana M. C.,Fantinel, Leonardo,Nachtigall, Fabiane M.,Bonacorso, Helio G.,Martins, Marcos A. P.
p. 2409 - 2415
(2007/10/03)

Retention and selectivity of teicoplanin stationary phases after copper complexation and isotopic exchange
Teicoplanin is a macrocyclic glycopeptide that is highly effective as a chiral selector for LC enantiomeric separations. Two possible interaction paths were investigated and related to solute retention and selectivity: (1) interactions with the only teicoplanin amine group and (2) role of hydrogen bonding interactions. Mobile phases containing 0.5 and 5 mM copper ions were used to try to block the amine group. In the presence of copper ions, it was found that the teicoplanin stationary phase has a decreased ability to separate most underivatized racemic amino acids. However, it maintained its ability to separate enantiomers that were not α - amino acids. It is established that there is little copper - teicoplanin complex formation. The effect of Cu2+ on the enantioseparation of some α - amino acids appears to be due to the fact that these solutes are good bidentate ligands and form complexes with copper ions in the mobile phase. Isotopic exchange with deuterium oxide was performed using acetonitrile - heavy water mobile phases. It was found that the retention times of all amino acids were lower with deuterated mobile phases. The retention times of polar or apolar molecules without amine groups were higher with deuterated mobiles phases. In all cases, the enantio-selectivity factors were unaffected by the deuterium exchange. It is proposed that the electrostatic interactions are decreased in the deuterated mobile phases and the solute-accessible stationary-phase volume is somewhat swollen by deuterium oxide. The balance of these effects is a decrease in the amino acid retention times and an increase in the apolar solute retention time. The enantio-selectivity factors of all of the molecules remain unchanged because all of the interactions are changed equally. We propose a new global quality criterion (the E factor) for comparing and evaluating enantiomeric separations.
Berthod,Valleix,Tizon,Leonce,Caussignac,Armstrong
p. 5499 - 5508
(2007/10/03)

AZOLE INHIBITORS OF CYTOKINE PRODUCTION
Compounds having the formula are useful for treating diseases that are prevented by or ameliorated with Interleukin-2, Interleukin-4, or Interleukin-5 production inhibitors.
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(2008/06/13)

Permucous preparation
A composition for permucosal administration characterized by containing Antago-3 or a physiologically acceptable salt thereof, and a sucrose fatty acid ester. With the composition for permucosal administration of the invention there is provided a long-term stable preparation having the high permucosal absorption of physiologically active peptide Antago-3 without irritation.
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(2008/06/13)

Beauveria bassiana ATCC 7159 contains an L-specific α-amino acid benzamidase
Biotransformation of a series of racemic N-benzoyl α-amino acids by the fungus Beauveria bassiana ATCC 7159 results in isolation of the corresponding D-amino acid benzamides in high enantiomeric purity and yield.
Holland, Herbert L.,Andreana, Peter R.,Salehzadeh-Asl, Reza,Van Vliet, Aaron,Ihasz, Nancy J.,Brown, Frances M.
p. 667 - 672
(2007/10/03)

Catalytic Hydrolysis of Peptides by Cerium(IV)
Oligopeptides are efficiently hydrolyzed by CeIV to the corresponding amino acids under mild conditions. The pseudo first-order rate constants for the hydrolysis of H-Gly-Phe-OH and H-Gly-Gly-OH at pH 7.0 and 50°C are 3.5 × 10-1 and 2.8 × 10-1 h-1, with [Ce(NH4)2(NO3)6]0 = 10 mM (the half-lives are 2.0 and 2.5 h). The catalytic activity of the CeIV is far greater than those of other lanthanide ions and nonlanthanide ions. No oxidative cleavage was observed under the reaction conditions. Catalytic turnover of the CeIV was also evidenced. The hydrolysis is fast especially when the substrates have no metal-coordinating side chains. Tripeptides and tetrapeptides are hydrolyzed at the similar rates as the dipeptides. In the hydrolysis of tripeptides, the amide linkage near the N-terminus is preferentially hydrolyzed. Neither the N-carbobenzyloxy derivative nor the amide of H-Gly-Phe-OH is hydrolyzed to a measurable extent, showing that both the terminal amino group and the carboxylate are coordinated to the CeIV ion. This complexation is further confirmed by 1H NMR spectroscopy. The CeIV ion is therefore one of the most active catalysts for peptide hydrolysis.
Takarada, Tohru,Yashiro, Mono,Komiyama, Makoto
p. 3906 - 3913
(2007/10/03)

A thermodynamic study of the hydrolysis of L-glutamine to (L-glutamate + ammonia) and of L-asparagine to (L-aspartate + ammonia)
Calorimetric enthalpies of reaction were measured for the two enzyme-catalyzed reactions, i.e., L-glutamine(aq) + H2O(l) = L-glutamate(aq) + ammonia(aq) (1) and L-asparagine(aq) + H2O(l) = L-aspartate(aq) + ammonia(aq) (2). The standard molar enthalpies for reference reactions involving specific species were computed using an equilibrium model that considered the multiplicity of ionic forms of the reactants and products. Using the thermodynamic quantities obtained for the reference reactions, the values of the apparent equilibrium constant for reactions 1 and 2 at 311.15 K and pH 7 were 250. In performing these calculations, it was assumed that there was no binding of Mg2+(aq) to any of the species involved in the reactions 1 and 2. The standard transformed Gibbs energy changes for these two reactions under physiological conditions were both -14 kJ/mole. The thermodynamic results were discussed with respect to the structural changes involved in these reactions.
Goldberg,Kishore,Kishore,Tewari
p. 1077 - 1090
(2007/10/03)

Compounds for and methods of inhibiting matrix metalloproteinases
The present invention relates to compounds of Formula I that inhibit matrix metalloproteinases and to a method of inhibiting matrix metalloproteinases using the compounds More particularly, the present invention relates to a method of treating diseases in which matrix metalloproteinases are involved such as multiple sclerosis, atherosclerotic plaque rupture, restenosis, aortic aneurysm, heart failure, periodontal disease, corneal ulceration, burns, decubital ulcers, chronic ulcers or wounds, cancer metastasis, tumor angiogenesis, osteoporosis, rheumatoid or osteoarthritis, renal disease, left ventricular dilatation, or other autoimmune or inflammatory diseases dependent upon tissue invasion by leukocytes.
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(2008/06/13)

Parenteral nutrition therapy with amino acids
Parenteral nutrition aqueous solutions are provided which preferably contain glutamine together with other organic nitrogen containing compounds. The respective concentrations of the compounds present in any given such solution are typically approximately multiples of the concentration of the same compounds as found in normal human plasma, and the respective mole ratios of various such compounds in any given such solution relative to one another are approximately the same mole ratio associated with the same compounds as found in normal human plasma. Processes for using such solutions are provided.
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(2008/06/13)

2-oxoethyl derivatives as immunosuppressants
A class of compounds that suppress human T-lymphocyte proliferation is disclosed. The active compounds essentially contain at least the following structure: STR1
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(2008/06/13)

Cosmetic composition
A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamine derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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(2008/06/13)

Microbial conversion of DL-5-substituted hydantoins to the corresponding L-amino acids by Bacillus stearothermophilus NS1122A
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Ishikawa,Mukohara,Watabe,Kobayashi,Nakamura
p. 265 - 270
(2007/10/02)

N-substituted mercaptopropanamide derivatives
Novel N-substituted mercaptopropanamide derivatives of the formula: STR1 wherein R1 is mercapto or a group convertible into mercapto when cleaved within the biobody, W is hydrogen atom, an alkyl or an aralkyl, R2 is an aryl which may optionally have substituent(s), a heterocyclic group which may optionally have substituent(s), or an alkyl which may optionally have substituent(s), X is a cycloalkylene, a cycloalkylidene, or a phenylene which may optionally have substituent(s) or may optionally be fused with other ring, and R3 is carboxyl or a group convertible into carboxyl when cleaved within the biobody, or a pharmaceutically acceptable salt thereof, and a solid solution of said N-substituted mercaptopropanamide derivative with an amino acid, which have excellent enkephalinase inhibitory activity and are useful for the treatment of mild to moderate pain, and a pharmaceutical composition containing said compounds as an active ingredient, and processes for preparing these compounds.
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(2008/06/13)

N-substituted mercaptopropanamide derivatives
Novel N-substituted mercaptopropanamide derivatives of the formula: STR1 wherein R1 is mercapto or a group convertible into mercapto when cleaved within the biobody, W is hydrogen atom, an alkyl or an aralkyl, R2 is an aryl which may optionally have substituent(s), a heterocyclic group which may optionally have substituent(s), or an alkyl which may optionally have substituent(s), X is a cycloalkylene, a cycloalkylidene, or a phenylene which may optionally have substituent(s) or may optionally be fused with other ring, and R3 is carboxyl or a group convertible into carboxyl when cleaved within the biobody, or a pharmaceutically acceptable salt thereof, and a solid solution of said N-substituted mercaptopropanamide derivative with an amino acid, which have excellent enkephalinase inhibitory activity and are useful for the treatment of mild to moderate pain, and a pharmaceutical composition containing said compounds as an active ingredient, and processes for preparing these compounds.
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(2008/06/13)

Chromatographic method for the determination of conditional equilibrium constants for the carbamate formation reaction from amino acids and peptides in aqueous solution
A novel and sensitive method has been developed and evaluated for the study of carbamate formation equilibria of amino acids and peptides in aqueous solution. The method is based on reversed-phase liquid chromatography with cetyltrimethylammonium bromide. The reliability of the method was established by comparing the results determined from the present study with the few data in the literature. The relaxation rate of the carbamate reaction was shown to be faster than the chromatographic distribution relaxation rate (seconds). As a result, the retention time of amine solutes is increased in the presence of CO2. Carbamate formation constants and mole fractions of carbamates at physiological pH of eleven L-α-amino acids and peptides were determined. No correlation between the formation constant and the ammonium pKa was found. There is significant dependence of the amount of a particular amino acid or peptide that exists as carbamate at pH 7.4 on the pKa of the ammonium group, however. This is due to mass action rather than reflecting the influence of pKa on the propensity of the amine to react with CO2. It is suggested that amino acids and peptides with ammonium pKa greater than 9.5 do not form significant amounts of carbamates in aqueous solution near neutral pH.
Chen, Jian-Ge,Sandberg, Mats,Weber, Stephen G.
p. 7343 - 7350
(2007/10/02)

Kinetic Resolution of Unnatural and Rarely Occuring Amino Acids: Enantioselective Hydrolysis of N-Acyl Amino Acids Catalyzed by Acylase I
Acylase I (aminoacylase; N-acylamino-acid amidohydrolase, EC 3.5.1.14, from porcine kidney and the fungus Aspergillus) is broadly applicable enzymatic catalyst for the kinetic resolution of unnatural and rarely occuring α-amino acids.Its enantioselectivity for the hydrolysis of N-acyl L-α-amino acids is nearly absolute, yet it accepts substrates having a wide range of structure and functionality.This paper reports the initial rates of enzyme-catalyzed hydrolysis of over 50 N-acyl amino acids and analogues, the stabilities of the enzymes in aqueous and aqueous/organic solutions, and the effects of different acyl groups and metal ions on the rates of enzymatic hydrolysis.Eleven α-amino and α-methyl α-amino acids were resolved on a 2-29-g scale.Crude L- and D-amino acid products had generally >90percent ee.The utility of resolved amino acids as chiral synthons was illustrated by the preparation of (R)- and (S)-1-butene oxide and the diastereoselective (cis:trans, 7-8:1) iodolactonization of three 2-amino-4-alkenoic acid derivatives.
Chenault, H. Keith,Dahmer, Juergen,Whitesides, George M.
p. 6354 - 6364
(2007/10/02)

Mechanism of Asymmetric Production of D-Amino Acids from the Corresponding Hydantoins by Pseudomonas sp.
The mechanism of asymmetric production of D-amino acids from the corresponding hydantoins by Pseudomonas sp.AJ-11220 was examined by investigating the properties of the enzymes involved in the hydrolysis of DL-5-substituted hydantoins.The enzymatic production of D-amino acids from the corresponding hydantoins by Pseudomonas sp.AJ-11220 involved the following two successive reactions; the D-isomer specific hydrolysis, i.e., the ring opening of D-5-substituted hydantoins to D-form N-carbamyl amino acids by an enzyme, D-hydantoin hydrolase (D-HYD hydrolase), followed by the D-isomer specific hydrolysis, i.e., the cleavage of N-carbamyl-D-amino acids to D-amino acids by an enzyme, N-carbamyl-D-amino acid hydrolase (D-NCA hydrolase).L-5-Substituted hydantoins not hydrolyzed by D-HYD hydrolase were converted to D-form 5-substituted hydantoins through spontaneous racemization under the enzymatic reaction conditions.It was proposed that almost all of the DL-5-substituted hydantoins were stoichiometrically and directly converted to the corresponding D-amino acids through the successive reactions of D-HYD hydrolase and D-NCA hydrolase in parallel with the spontaneous racemization of L-5-substituted hydantoins to those of DL-form.
Yokozeki, Kenzo,Kubota, Koji
p. 721 - 728
(2007/10/02)

Chemical Conversion of L-α,ο-Diamino Acids to L-ο-Carbamoyl-α-amino Acids by Ruthenium tetroxide Oxidation
Ruthenium tetroxide oxidation of N,C-protected derivatives of L-2,4-diaminobutyric acid, L-ornitine and L-lisine was carried out two-phase conditions and the corresponding imides, formed through the oxidation of the methylene adjacent to the ο-amino group, were obtained in good yields.Removal of the protecting groups from the products gave L-asparagine, L-glutamine and L-2-aminoadipic acid 6-amide, respectively.Thus the first chemical conversion of L-α,ο-diamino acids into the corresponding L-ο-carbamoyl-α-amino acids without racemization has been established.L-2-Aminoadipic acid 6-amide was further converted to L-2-aminoadipic acid by acid hydrolysis.This represents a convenient method for the synthesis of L-2-aminoadipic acid starting from L-lisine.Keywords - oxidation; ruthenium tetroxide; L-α-amino acid synthesis; N-protecting group; ruthenium tetroxide; L-α,ο-diamino acid; L-ο-carbamoiyl-α-amino acid; L-2-aminoadipicacid
Yoshifuji, Shigeyuki,Tanaka, Ken-ichi,Nitta, Yoshihiro
p. 2994 - 3001
(2007/10/02)

PROPERTIES OF Nα,Nca-DI-TERT-BUTYLOXYCARBONYL-ω-CARBAMOYL-α-AMINO ACIDS AND DIRECT SYNTHESIS OF PROTECTED HOMOGLUTAMIC ACID DERIVATIVES
The protected carboxamide function of Nα,Nca-di-tert-butyloxy-carbonyl-ω-carbamoyl-α-amino acids worked well with nucleophilic reagents.Applying this novel reactivity, we developed an efficient synthetic route to Nα-tert-butyloxycarbonylhomoglutamic acid and its derivatives, including Nα-tert-butyloxycarbonylhomoglutamic acid δ-benzyl ester, from Nα,Nca-di-tert-butyloxycarbonylhomoglutamine.KEYWORDS - protected homoglutamic acid synthesis; Nca-tert-butyloxycarbonylated carboxamide; hydrolysis; selective deprotection; Nα-tert-butyloxycarbonylhomoglutamic acid δ-benzyl ester; Nα-tert-butyloxycarbonylhomoglutamic acid α-tert-butyl ester; Nα-tert-butyloxycarbonylhomoglutamine; optical purity
Sakura, Naoki,Hirose, Kyoko,Hashimoto, Tadashi
p. 3506 - 3509
(2007/10/02)

Alternative synthesis of porcine secretin and apparent autolysis of the product
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Kiyama,Kitagawa,Akita,Chey,Ayalp,Otsuki,Funakoshi,Fujii,Yajima
p. 3205 - 3217
(2007/10/02)

3,5-DINITRO-1-(4-NITROPHENYL)-4-PYRIDONE, A NOVEL AND CONVENIENT PROTECTING REAGENT FOR PRIMARY AMINES.
Crystalline derivatives of the following L-amino acids modified by 2,5-dinitro-4-pyridone have been prepared: glycine, alanine, valine, leucine, isoleucine, phenylalanine, serine, threonine, tyrosine, aspartic acid, asparagine, glutamic acid, glutamine, tryptophan, histidine, arginine, methionine and lysine. The modified L-amino acids (DNPY-L-amino acids) could be purified by recrystallization and were characterized by **1H-NMR, IR and UV spectral data. The molar rotation of the DNPY-L-amino acids varied from 2 to 100 times those of the parent amino acids. The effectiveness of 3,5-dinitro-1-(4-nitrophenyl)-4-pyridone as an amino-protecting reagent of L-amino acids is described.
Matsumura,Kobayashi,Nishikawa,Ariga,Tohda,Kawashima
p. 1961 - 1965
(2007/10/02)

Synthesis of a Monocyclic β-Lactam Stereospecifically Labelled at C-4
In connection with biosynthetic studies, the β-lactams (5; 4-HR = 2H) and (5; 3-H = 4-HS = 2H) have been synthesized.The 1H and 2H n.m.r. spectra of these compounds confirm the assignment of the stereochemistry to the two hydrogens at C-4 of monocyclic β-lactams such as nocardicin A.Samples of the amino-acid L-asparagine stereospecifically labelled at C-3 have been made in the course of this work.
Gani, David,Young, Douglas W.,Carr, David M.,Poyser, J. Philip,Sadler, Ian H.
p. 2811 - 2814
(2007/10/02)