title: On the DD-carboxypeptidase enzyme system of Streptomyces strain K15.
abstract: Streptomyces K15 possesses a set of exocellular and cell-bound D-alanyl-D-alanine carboxypeptidases. Four of them have been isolated to the stage where each enzyme preparation contains on single penicillin-binding protein. The exocellular 54000-Mr enzyme is extremely sensitive to benzylpenicillin and performs low transpeptidase activity on the carbonyl-donor/amino-acceptor tetrapeptide ACLLys(Gly)-DAla-DAla. The exocellular 40 000-Mr enzyme and the two lysozyme-releasable 40 000-Mr and 38 000-Mr enzymes are moderately sensitive to benzylpenicillin and have a high propensity to catalyse dimer formation from the aforementioned tetrapeptide monomer.
mesh_terms: D002268:Carboxypeptidases / Q000378:metabolism*; D002473:Cell Wall; D008970:Molecular Weight; D002267:Muramoylpentapeptide Carboxypeptidase / Q000302:isolation & purification / Q000378:metabolism*; D010400:Penicillin G; D013302:Streptomyces / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D002268:Carboxypeptidases; D002267:Muramoylpentapeptide Carboxypeptidase; D010400:Penicillin G