Specificity and reversibility of the transpeptidation reaction catalyzed by the Streptomyces R61 D‐Ala‐D‐Ala peptidase

• Published in: Protein science 2005-11, Vol.14 (11), p.2922-2928
• Main Authors: Rhazi, Noureddine, Delmarcelle, Michael, Sauvage, Eric, Jacquemotte, Françoise, Devriendt, Kris, Tallon, Valérie, Ghosez, Léon, Frère, Jean‐Marie
• Format: Article
• Language: English
• Subjects: active sites; beta-lactam antibiotic; Biochemistry, biophysics & molecular biology; Biochimie, biophysique & biologie moléculaire; Catalysis; D-Ala-D-Ala peptidase; Dipeptides - chemistry; Dipeptides - metabolism; enzymes; For the Record; hydrodynamics; kinetics; Life sciences; mechanism; penicillin binding protein; Peptides - chemistry; Peptides - metabolism; reversibility; Sciences du vivant; Serine-Type D-Ala-D-Ala Carboxypeptidase - chemistry; Serine-Type D-Ala-D-Ala Carboxypeptidase - metabolism; specificity; Streptomyces; Streptomyces - enzymology; Substrate Specificity; thermodynamics; transpeptidation; β‐lactam antibiotic
• ISSN: 0961-8368; 1469-896X; 1469-896X
• DOI: 10.1110/ps.051641005

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 reversibilty of the transpeptidation reaction.