- A novel phenylalanine ammonia-lyase from Pseudozyma antarctica for stereoselective biotransformations of unnatural amino acids
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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
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p. 185 - 194
(2020/04/28)
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- Bio-inspired enantioselective full transamination using readily available cyclodextrin
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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
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p. 4203 - 4208
(2017/02/05)
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- Ligand-Enabled β-C–H Arylation of α-Amino Acids Without Installing Exogenous Directing Groups
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Herein we report acid-directed β-C(sp3)-H arylation of α-amino acids enabled by pyridine-type ligands. This reaction does not require the installation of an exogenous directing group, is scalable, and enables the preparation of Fmoc-protected unnatural amino acids in three steps. The pyridine-type ligands are crucial for the development of this new C(sp3)-H arylation.
- Chen, Gang,Zhuang, Zhe,Li, Gen-Cheng,Saint-Denis, Tyler G.,Hsiao, Yi,Joe, Candice L.,Yu, Jin-Quan
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p. 1506 - 1509
(2017/02/05)
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- Novel chiral open-chain pyridoxamine catalyst and synthesis method and application thereof
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The invention relates to a novel chiral open-chain pyridoxamine catalyst and a synthesis method and application thereof. The structural general formula of the pyridoxamine catalyst is shown in the specification, wherein R1, R2, R3 and R4 are one of hydrogen, C1-24 alkyl, C1-24 alkyl containing substituent groups, substances shown in the specification and halogen, the substituent groups on C1-24 alkyl are a substance shown in the specification or a substance shown in the specification or a substance shown in the specification or O-Rw or S-Rw' or halogen, and Rx, Rx', Ry, Ry', Ry'', Rz, Rz', Rw and Rw' are one of hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, tertiary butyl, cyclopentyl, cyclohexyl, cycloheptyl, phenyl, benzyl, (1-phenyl)ethyl, 1-naphthyl, 2-naphthyl and halogen. Compared with the prior art, the pyridoxamine catalyst can achieve rapid and efficient synthesis of chiral amino acid, the preparation raw materials are easy to obtain, reaction conditions are mild, cost is low, and when the novel chiral open-chain pyridoxamine catalyst is used for a transamination reaction, the conditions are mild, and the reaction is stable.
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Paragraph 0175; 0176; 0177; 0178; 0193; 0194; 0195; 0196
(2017/01/19)
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- A new type of chiral-pyridoxamines for catalytic asymmetric transamination of α-keto acids
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A new type of chiral pyridoxamines bearing an adjacent chiral stereocenter has been developed via multi-step synthesis. The pyridoxamines displayed catalytic activity in asymmetric transamination of α-keto acids to give a variety of optically active amino acids in 27–78% yields with 34–62% ee's under very mild conditions. This work provides a synthetic strategy to construct new chiral pyridoxamines using bromopyridine 7 as a key synthon and also represents an early example of the applications of chiral pyridoxamines in asymmetric catalysis.
- Chen, Jianfeng,Zhao, Junyu,Gong, Xing,Xu, Dongfang,Zhao, Baoguo
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supporting information
p. 4612 - 4615
(2016/09/23)
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- The bacterial ammonia lyase EncP: A tunable biocatalyst for the synthesis of unnatural amino acids
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Enzymes of the class I lyase-like family catalyze the asymmetric addition of ammonia to arylacrylates, yielding high value amino acids as products. Recent examples include the use of phenylalanine ammonia lyases (PALs), either alone or as a gateway to deracemization cascades (giving (S)- or (R)-α-phenylalanine derivatives, respectively), and also eukaryotic phenylalanine aminomutases (PAMs) for the synthesis of the (R)-β-products. Herein, we present the investigation of another family member, EncP from Streptomyces maritimus, thereby expanding the biocatalytic toolbox and enabling the production of the missing (S)-β-isomer. EncP was found to convert a range of arylacrylates to a mixture of (S)-α- and (S)-β-arylalanines, with regioselectivity correlating to the strength of electron-withdrawing/-donating groups on the ring of each substrate. The low regioselectivity of the wild-type enzyme was addressed via structure-based rational design to generate three variants with altered preference for either α- or β-products. By examining various biocatalyst/substrate combinations, it was demonstrated that the amination pattern of the reaction could be tuned to achieve selectivities between 99:1 and 1:99 for β:α-product ratios as desired.
- Weise, Nicholas J.,Parmeggiani, Fabio,Ahmed, Syed T.,Turner, Nicholas J.
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supporting information
p. 12977 - 12983
(2015/10/28)
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- Efficient kinetic resolution of amino acids catalyzed by lipase AS 'Amano' via cleavage of an amide bond
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Herein the efficient kinetic resolution of non-natural alpha-amino acids catalyzed by lipase AS 'Amano' via cleaving the amide bond is reported. The starting materials were the corresponding amino acid amides and the amino acids were generated with ees of up to 99% with E values of >600. These results indicated that the lipase AS 'Amano' could be a powerful amide hydrolase for the kinetic resolution of amino acid starting from the corresponding amino acid amides.
- Wang, Bo,Liu, Yanfeng,Zhang, Dela,Feng, Yuhong,Li, Jiacheng
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p. 1338 - 1342,5
(2020/09/16)
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- Mechanistic approach of the difference in non-enzymatic hydrolysis rate between the L and D enantiomers of no-carrier added 2-[18F] fluoromethyl-phenylalanine
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No-carrier added (n.c.a.) 2-[18F]fluoromethyl-l-phenylalanine was found to be very sensitive to hydrolysis in aqueous solutions. This problem was solved partially by the addition of calcium ions (0.04M), increasing the shelf-life to at least 6h. In this paper the defluorination reaction was studied in detail to elucidate its mechanism. Therefore, L and D enantiomers of 2-[18F]FMP and 4-[18F]FMP were synthesized, as well as 2-[18F]fluoromethyl-phenethylamine and 4-[18F] fluoromethyl-phenethylamine, both decarboxylated 'mimetic' molecules of the amino acid analogues. Radiosynthesis, using a customized Scintomics automatic synthesis hotboxthree module, resulted in a high overall yield and a radiochemical purity of >99%. The defluorination rates of all compounds were studied by HPLC. The L enantiomer of n.c.a 2-[18F]FMP defluorinated seven times faster than the D enantiomer and 2-[18F]fluoromethyl- phenethylamine. Both enantiomers of 4-[18F]FMP and 4-[ 18F]fluoromethyl-phenethylamine were stable. From these data, the reaction mechanism, involving two distinct intramolecular interactions, was derived. First, the interaction between the amine and the benzylic fluorine weakens the carbon-fluorine bond. Secondly, the formation of a second hydrogen bridge between the carboxyl group and one of the benzylic hydrogen atoms renders the fluorine atom even more susceptible to hydrolysis. The latter interaction induces an additional chiral center. The probability of its formation differs considerably between L and D enantiomers of n.c.a. 2-[18F]FMP, which explains the difference in hydrolysis rate. Copyright
- Kersemans, Ken,Mertens, John,De Proft, Frank,Geerlings, Paul
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scheme or table
p. 80 - 85
(2011/10/30)
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- Phenylalanine aminomutase-catalyzed addition of ammonia to substituted cinnamic acids: A route to enantiopure α- and β-amino acids
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(Chemical Equation Presented) An approach is described for the synthesis of aromatic α- and β-amino acids that uses phenylalanine aminomutase to catalyze a highly enantioselective addition of ammonia to substituted cinnamic acids. The reaction has a broad scope and yields substituted α- and β-phenylalanines with excellent enantiomeric excess. The regioselectivity of the conversion is determined by substituents present at the aromatic ring. A box model for the enzyme active site is proposed, derived from the influence of the hydrophobicity of substituents on the enzyme affinity toward various substrates.
- Szymanski, Wiktor,Wu, Bian,Weiner, Barbara,De Wildeman, Stefaan,Feringa, Ben L.,Janssen, Dick B.
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supporting information; experimental part
p. 9152 - 9157
(2010/03/01)
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- Use of whole cell culture of Aeromonas sp. as enantioselective scavenger: A facile preparation of l-amino acid derivatives in high enantiomeric excess
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The bacterium Aeromonas sp. (CGMCC 2226) can enantioselectively scavenge d-isomer, making l-amino acid derivatives (AADs) in high ee. The enantioselective scavenger (ES) has shown a broad substrate scope. Eleven l-AADs, Phe derivatives substituted with methyl-, mono- and dichloro-, bromo-, and nitro-group, were produced in high ee from corresponding racemates.
- Zhang, Zizhang
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experimental part
p. 1129 - 1131
(2009/09/04)
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- Enantioselective synthesis of non-natural amino acids using phenylalanine dehydrogenases modified by site-directed mutagenesis
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The substrate scope of three mutants of phenylalanine dehydrogenase as biocatalysts for the transformation of a series of 2-oxo acids, structurally related to phenylpyruvic acid, to the analogous -amino acids, non-natural analogues of phenylalanine, has been investigated. The mutant enzymes are more tolerant than the wild type enzyme of the non-natural substrates, especially those with substituents at the 4-position on the phenyl ring. Excellent enantiocontrol resulted in all cases.
- Busca, Patricia,Paradisi, Francesca,Moynihan, Eamonn,Maguire, Anita R.,Engel, Paul C.
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p. 2684 - 2691
(2007/10/03)
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- Acylase I catalysed hydrolysis of para-substituted (S)-phenylalanine derivatives from mixtures of the racemic ortho- and para-substituted isomers
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para-Substituted (S)-phenylalanines may be obtained by treatment of the corresponding mixtures of ortho- and para-substituted N-acetyl-(RS)- phenylalanines with Acylase I from porcine kidney. The selectivity of the enzyme may be attributed to its evolution to digest peptide derivatives of (S)-phenylalanine and (S)-tyrosine.
- Easton, Christopher J.,Harper, Jason B.
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p. 5269 - 5272
(2007/10/03)
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- Dose-response relations for unnatural amino acids at the agonist binding site of the nicotinic acetylcholine receptor: Tests with novel side chains and with several agonists
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Structure-function relations in the nicotinic acetylcholine receptor are probed using a recently developed method based on chemical synthesis of nonsense suppressor tRNAs with unnatural amino acid residues, site-directed incorporation at nonsense codons in Xenopus laevis oocytes, and electrophysiological measurements. A broad range of unnatural amino acids, as many as 14 at a given site, are incorporated at three sites, α93, α190, and α198, all of which are tyrosine in the wild-type receptor and are thought to contribute to the agonist binding site. Confirming and expanding upon earlier studies using conventional mutagenesis, the three tyrosines are shown to be in substantially different structural microenvironments. In particular, a crucial role is established for the hydroxyl group of α-Tyr93, whereas a variety of substituents are functional at the analogous position of αTyr198. Interestingly, consideration of three different agonists (acetylcholine, nicotine, and tetramethylammonium) does not discriminate between these two best-characterized binding site residues. In addition, double-mutation studies establish the independent effects of mutations at the pore region (second transmembrane region) and at the agonist binding site, and this observation leads to a novel strategy for adjusting EC50 values. These results establish the broad generality and great potential of the unnatural amino acid methodology for illuminating subtle structural distinctions in neuroreceptors and related integral membrane proteins.
- Kearney, Patrick C.,Nowak, Mark W.,Zhong, Wenge,Silverman, Scott K.,Lester, Henry A.,Dougherty, Dennis A.
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p. 1401 - 1412
(2007/10/03)
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- Analogues of 8-D-homoarginine vasopressin
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Analogues of 8-D-homoarginine vasopressin were prepared with the general formula STR1 where X is L-O-methyltyrosine, L-p-ethylphenylalanine, D-p-ethylphenylalanine, L-p-methylphenylalanine or D-methylphenylalanine and R is cysteine or β-mercaptopropionic acid. These vasopressin analogues exhibited an increased affinity to uterus receptors for oxytocin, where they acted as ocytocin antagonists. Moreover, the analogues of deamino vasopressin have a significantly reduced antidiuretic activity in comparison with [8-D-arginine]vasopressin.
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- Enzymatic peptide synthesis in frozen aqueous systems: Use of N(α)-unprotected unusual acyl donors
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α-Chymotrypsin (EC 3.4.21.1) was used for catalyzing the reaction of various N(α)-unprotected non-coded phenylalanine ester derivatives with H-Leu-NH2 and H-Arg-NH2 in frozen aqueous solution at -15°C. Compared with reactions at room temperature, a significant yield increasing effect could be established. The kinetic parameters of ester hydrolysis show that most of the unusual acyl donors (compared with the coded phenylalanine methyl ester) are well accepted substrates for α-chymotrypsin.
- Gerisch,Jakubke,Kreuzfeld
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p. 3039 - 3045
(2007/10/03)
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