| abstract |
ABSTRACT A peptide having the formula A-B wherein A represents an N-terminal protected amino acid residue or an optionally N-terminal protected peptide residue and B represents an optionally C-terminal protected amino acid residue, is prepared by reacting a substrate component selected from the group consisting of (a) amino acid esters, peptide esters and depsipeptides of the formula A-OR1, A-SR1 or A-SeR' wherein A is as defined above and R1 represents alkyl , aryl, heteroaryl, aralkyl or an .alpha.-des-amino fragment of an amino residue, (b) optionally N-substituted amino acid amides and peptide amides of the formula A-NR2R2' wherein A is as defined above and R2 and R2' are independently selected from hydrogen, alkyl, aryl, heteroaryl or aralkyl, and with an amine component selected from the group consisting of (a) amino acids of the formula H-B-OH, (b) optionally N-substituted amino acid amides of the formula H-B-NR3R3' wherein B is an amino acid residue and R3 and R3' are independently selected from hydrogen, hydroxy, amino or alkyl, aryl, heteroaryl or aralkyl, and (c) amino acid esters of the formula H-B-OR4, H-B-SR4 or H-B-SeR4 wherein B is an amino acid residue and R represents alkyl, aryl, heteroaryl and aralkyl, in the presence of a carboxypeptidase enzyme in an aqueous solution or dispersion having a pH from 5 to 10.5, preferably at a tempe-rature of from 20 to 50°C, to form a peptide, and subsequently cleaving a group H,-NR3R3 ,-OR4,-SR4 or -SeR4, if desired. |