78306-92-0Relevant articles and documents
In vitro evolution of an l-amino acid deaminase active on l-1-naphthylalanine
Melis, Roberta,Rosini, Elena,Pirillo, Valentina,Pollegioni, Loredano,Molla, Gianluca
, p. 5359 - 5367 (2018/10/23)
l-Amino acid deaminase from Proteus myxofaciens (PmaLAAD) is a promising biocatalyst for enantioselective biocatalysis that can be exploited to produce optically pure d-amino acids or α-keto acids. In this study, we improved the catalytic efficiency of PmaLAAD on l-1-naphthylalanine (l-1-Nal), a synthetic amino acid of biotechnological interest. Eight evolvable positions were identified by a molecular docking and evolutionary conservation analysis. These positions were subjected to site-saturation mutagenesis, producing smaller but smarter libraries of variants. The best variant (F318A/V412A/V438P PmaLAAD) possesses a ～5-fold lower Km (0.17 mM) and a ～7-fold higher catalytic efficiency (9.2 s-1 mM-1) on l-1-Nal than the wild-type enzyme. Molecular docking analysis suggests that the substitutions increase the active site volume, allowing better binding of the bulky l-1-Nal substrate. Bioconversion reactions showed that the F318A/V412A/V438P PmaLAAD variant outperforms the wild-type enzyme in the deracemization of d,l-1-Nal: the complete conversion of 0.6 mM of the l-enantiomer was achieved in about 15 min, which is ～7.5-fold faster than the wild-type enzyme. In addition, the F318A/V412A/V438P PmaLAAD is efficiently employed, together with the M213G d-amino acid oxidase variant, to produce 1-naphtylpyruvate from racemic d,l-1-Nal in one pot.
Deracemization and Stereoinversion of α-Amino Acids by l-Amino Acid Deaminase
Rosini, Elena,Melis, Roberta,Molla, Gianluca,Tessaro, Davide,Pollegioni, Loredano
, p. 3773 - 3781 (2017/11/13)
Enantiomerically pure α-amino acids are compounds of primary interest for the fine chemical, pharmaceutical, and agrochemical sectors. Amino acid oxidases are used for resolving d,l-amino acids in biocatalysis. We recently demonstrated that l-amino acid deaminase from Proteus myxofaciens (PmaLAAD) shows peculiar features for biotechnological applications, such as a high production level as soluble protein in Escherichia coli and a stable binding with the flavin cofactor. Since l-amino acid deaminases are membrane-bound enzymes, previous applications were mainly based on the use of cell-based methods. Now, taking advantage of the broad substrate specificity of PmaLAAD, a number of natural and synthetic l-amino acids were fully converted by the purified enzyme into the corresponding α-keto acids: the fastest conversion was obtained for 4-nitrophenylalanine. Analogously, starting from racemic solutions, the full resolution (ee >99%) was also achieved. Notably, d,l-1-naphthylalanine was resolved either into the d- or the l-enantiomer by using PmaLAAD or the d-amino acid oxidase variant having a glycine at position 213, respectively, and was fully deracemized when the two enzymes were used jointly. Moreover, the complete stereoinversion of l-4-nitrophenylalanine was achieved using PmaLAAD and a small molar excess of borane tert-butylamine complex. Taken together, recombinant PmaLAAD represents an l-specific amino acid deaminase suitable for producing the pure enantiomers of several natural and synthetic amino acids or the corresponding keto acids, compounds of biotechnological or pharmaceutical relevance. (Figure presented.).
COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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Page/Page column 45-49; 61, (2010/12/31)
The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
Chiral salen-metal complexes as novel catalysts for the asymmetric synthesis of α-amino acids under phase transfer catalysis conditions
Belokon, Yuri N,North, Michael,Churkina, Tatiana D,Ikonnikov, Nikolai S,Maleev, Victor I
, p. 2491 - 2498 (2007/10/03)
Chiral salen-metal complexes have been tested as catalysts for the C-alkylation of Schiff's bases of alanine and glycine esters with alkyl bromides under phase-transfer conditions (solid sodium hydroxide, toluene, ambient temperature, 1-10 mol% of the catalyst). The best catalyst, which was derived from a Cu(II) complex of (1R, 2R or 1S,2S)-[N,N′-bis(2′-hydroxybenzylidene)]-1,2-diaminocyclohexane, gave α-amino and α-methyl-α-amino acids with enantiomeric excesses of 70-96%.
Asymmetric synthesis of α-amino acids by copper-catalyzed conjugate addition of Grignard reagents to optically active carbamatoacrylates
Lander, Peter A.,Hegedus, Louis S.
, p. 8126 - 8132 (2007/10/02)
Optically active ene carbamates were α-lithiated by lithium tetramethylpiperidide in the presence of trialkylstannyl chlorides to produce α-stannylated compounds. These underwent facile palladium-catalyzed couplings with acid chlorides to produce α-keto ene carbamates in good yield. Treatment of the α-stannyl ene carbamates with butyllithium followed by quenching with carbon dioxide and esterification gave optically active carbamatoacrylates. Copper-catalyzed addition of tert-butyl-, 1-naphthyl-, 2-propenyl-, p-methoxyphenyl-, (trimethylsilyl)methyl-, cyclohexyl-, 1-adamantyl-, and isopropyl Grignard reagents followed by quenching at -10 to 25°C and removal of the protecting groups gave the corresponding α-amino acids in 70-90% yield and 73-97% ee. Quenching the reaction at low temperature resulted in little if any asymmetric induction.
Synthesis and biological activities of cholecystokinin analogues substituted in position 30 by 3-(1-naphthyl)-L-alanine [Nal(1)] or 3-(2-naphthyl)-L-alanine [Nal(2)]
Rodriguez,Bernad,Galas,Lignon,Laur,Aumelas,Martinez
, p. 245 - 253 (2007/10/02)
Acetyl derivatives of ethyl esters of 3-(1-naphthyl)-D,L-alanine and 3-(2-naphthyl)-D,L-alanine were synthesized through a malonic condensation. Resolution of these derivatives by subtilisin Carlsberg followed by acid hydrolysis afforded the 2 optical isomers of 3-(1-naphthyl)-alanine [Nal(1)] and 3-(2-naphthyl)-alanine [Nal(2)]. The L enantiomers of these amino acids were incorporated into the sequence of cholecystokinin in place of the tryptophan in position 30. The cholecystokinin analogues thus obtained behaved as full agonists, with reduced potencies on rat pancreatic acini and on guinea pig brain membranes, by about one order of magnitude for the Nal(1) derivative, as compared to the potent parent compound Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-Asp-Phe-NH2.
