title: Streptomyces K15 DD-peptidase-catalysed reactions with suicide beta-lactam carbonyl donors.
abstract: The values of the kinetic parameters that govern the interactions between the Streptomyces K15 DD-peptidase and beta-lactam compounds were determined by measuring the inactivating effect that these compounds exert on the transpeptidase activity of the enzyme and, in the case of [14C]benzylpenicillin and [14C]cefoxitin, by measuring the amounts of acyl-enzyme formed during the reaction. K15 DD-peptidase binds benzylpenicillin or cefoxitin at a molar ratio of 1:1. Benzylpenicilloate is the major product released during breakdown of the acyl-enzyme formed with benzylpenicillin. Benzylpenicillin is not a better acylating agent than the amide Ac2-L-Lys-D-Ala-D-Ala and ester Ac2-L-Lys-D-Ala-D-lactatecarbonyl-donor substrates. beta-Lactam compounds possessing a methoxy group on the alpha-face of the molecule show high inactivating potency.
mesh_terms: D000215:Acylation; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D002268:Carboxypeptidases / Q000378:metabolism*; D002440:Cefoxitin / Q000378:metabolism; D007700:Kinetics; D002267:Muramoylpentapeptide Carboxypeptidase / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism; D010400:Penicillin G / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D000900:Anti-Bacterial Agents; D009842:Oligopeptides; C033530:N(alpha), N-(epsilon)-diacetyl-lysyl-alanyl-alanine; D002440:Cefoxitin; D002268:Carboxypeptidases; D002267:Muramoylpentapeptide Carboxypeptidase; D010400:Penicillin G