STREPTOMYCES K15 ACTIVE-SITE SERINE DD-TRANSPEPTIDASE - SPECIFICITY PROFILE FOR PEPTIDE, THIOL ESTER AND ESTER CARBONYL DONORS AND PATHWAYSOF THE TRANSFER-REACTIONS
J. Grandchamps et al., STREPTOMYCES K15 ACTIVE-SITE SERINE DD-TRANSPEPTIDASE - SPECIFICITY PROFILE FOR PEPTIDE, THIOL ESTER AND ESTER CARBONYL DONORS AND PATHWAYSOF THE TRANSFER-REACTIONS, Biochemical journal, 307, 1995, pp. 335-339
The Streptomyces K15 transferase is a penicillin-binding protein presu
med to be involved in bacterial wall peptidoglycan cross-linking. It c
atalyses cleavage of the peptide, thiol ester or ester bond of carbony
l donors Z-R(1)-CONH-CHR(2)-COX-CHR(3)-COO- (where X is NH, S or O) an
d transfers the electrophilic group Z-R(1)-CONH-CHR(2)-CO to amino acc
eptors via an acyl-enzyme intermediate. Kinetic data suggest that the
amino acceptor behaves as a simple alternative nucleophile at the leve
l of the acyl-enzyme in the case of thiol ester and ester donors, and
that it binds to the enzyme . carbonyl donor Michaelis complex and inf
luences the rate of enzyme acylation by the carbonyl donor in the case
of amide donors. Depending on the nature of the scissile bond, the en
zyme has different requirements for substituents at positions R(1), R(
2) and R(3).