29701-42-6Relevant academic research and scientific papers
Determination of the Enantioselectivity for Kinetically Controlled Condensations Catalysed by Amidases and Peptidases
Galunsky, Boris,Kasche, Volker
, p. 1115 - 1119 (2002)
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.
PEPTIDE SYNTHESIS CATALYZED BY NATIVE PROTEINASE K IN WATER-MISCIBLE ORGANIC SOLVENTS WITH LOW WATER CONTENT
Cerovsky, Vaclav,Martinek, Karel
, p. 2027 - 2041 (2007/10/02)
Rection of Ac-Tyr-OEt with HBr.Gly-NH2, catalysed by free proteinase K in various water-miscible organic solvents in the presence of triethylamine and 5 mol percent of water, was studied.Some aliphatic alcohols and acetonitrile proved to be suitable solvents.The effect of water content (2 percent - 20 percent) on the synthesis of Ac-Tyr-Gly-NH2 was studied using acetonitrile as solvent.Lowering of the water content to 5 percent or 2 percent led to almost 100 percent yield of the desired dipeptide; higher water content accelerated the reaction reducing at the same time the yield of Ac-Tyr-Gly-NH2 due to the concurrent hydrolysis of the ester Ac-Tyr-OEt.No reaction was observed in the absence of base (triethylamine), wereas an excess of base only retarded the reaction.The enzyme is capable of catalyzing the peptide bond synthesis with N-acylamino acids or N-acyl peptides as acylating components, which may contain all types of L-amino acid residues (except Pro) in the P1 position.However, the peptide bond synthesis depends strongly on the amino component composition, particularly on the amino acid residue in the P'1 position.Only amides of glycine and of hydrophillic amino acids were acylated with Ac-Tyr-OEt; amides of hydrophobic amino acids enter the reaction only reluctantly or not at al.The presence of Leu or Phe in position P'2 and Leu in position P'3 has not so negative effect on acylation of the amino component as has in presence in the P'1 position.The choice of protecting groups for the α-carboxyl of the amino component is restricted only to amide and in some cases its undesired enzymatic removal was observed.Unprotected peptides seem to be suitable amino components.
