Specificity and reversibility of the transpeptidation reaction catalyzed by the Streptomyces R61 D-Ala-D-Ala peptidase.
The specificity of the Streptomyces R61 penicillin-sensitive D-Ala-D-Ala peptidase has been re-examined with the help of synthetic substrates. The products of the transpeptidation reactions obtained with Gly-L-Xaa dipeptides as acceptor substrates are themselves poor substrates of the enzyme. This is in apparent contradiction with the classically accepted specificity rules for D-Ala-D-Ala peptidases. The Gly-L-Xaa dipeptide is regenerated by both the hydrolysis and transpeptidation reactions. The latter reaction is observed when another Gly-L-Xaa peptide or D-Alanine are supplied as acceptors. Utilization of substrates in which the terminal -COO(-) group has been esterified or amidated shows that a free carboxylate is not an absolute prerequisite for activity. The results are discussed in the context of the expected reversibility of the transpeptidation reaction.
Rhazi
Noureddine
N
Centre d'Ingénierie de Protéines, Université de Liège, Institut de Chimie B6, Sart-Tilman, B-4000 Liège, Belgium.
Delmarcelle
Michael
M
Sauvage
Eric
E
Jacquemotte
Françoise
F
Devriendt
Kris
K
Tallon
Valérie
V
Ghosez
Léon
L
Frère
Jean-Marie
JM
D002384:Catalysis; D004151:Dipeptides / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase / Q000737:chemistry* / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology*; D013379:Substrate Specificity
D004151:Dipeptides; D010455:Peptides; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase