- Penicillin acylase-catalyzed peptide synthesis in aqueous medium: A chemo-enzymatic route to stereoisomerically pure diketopiperazines
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A range of non-natural dipeptides of the general formula D-(-)-phenylglycyl-L-X, where X is a natural α-amino acid, have been prepared by penicillin acylase-catalyzed synthesis in aqueous medium from D-(-)-phenylglycine amide and the corresponding amino acids. The conversion of the dipeptides to the corresponding dipeptide esters, followed by their subsequent spontaneous cyclization afforded the corresponding stereoisomerically pure diketopiperazines.
- Khimiuk, Andrei Y.,Korennykh, Alexei V.,Van Langen, Luuk M.,Van Rantwijk, Fred,Sheldon, Roger A.,Svedas, Vytas K.
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p. 3123 - 3128
(2007/10/03)
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- Determination of the Enantioselectivity for Kinetically Controlled Condensations Catalysed by Amidases and Peptidases
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For kinetically controlled synthetic reactions catalysed by amidases and peptidases, the enantio- or stereoselectivity determined from initial rates with racemic mixtures (Esyn, rac) was found to differ from the enantioselectivity determined from measurements with isolated enantiomeric nucleophiles (Esyn). This was observed for kinetically controlled condensation of R-phenyglycineamide with S-, R- and racemic Phe and S-, R- and racemic Leu catalysed by penicillin amidase from E. coli and for kinetically controlled condensation of Nα-acetyl-S-tyrosine ethyl ester with S-, R- and racemic AlaNH2 catalysed by bovine α-chymotrypsin. It is shown that only Esyn, rac determined with racemic nucleophiles is an intrinsic enzyme property which should be used to study the influence of the primary structure, physicochemical parameters and immobilisation on biocatalyst enantioselectivity in kinetically controlled synthetic reactions catalysed by these enzymes.
- Galunsky, Boris,Kasche, Volker
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p. 1115 - 1119
(2007/10/03)
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