title: The beta-lactamase of Streptomyces cacaoi: interaction with cefoxitin and beta-iodopenicillanate.
abstract: Cefoxitin was a very poor substrate for the beta-lactamase of Streptomyces cacaoi (kcat = 2.7 x 10(-4) s-1). In the presence of nitrocefin, a good substrate, cefoxitin behaved as a transient inactivator by immobilizing a large proportion of the enzyme as the acyl enzyme intermediate. The enzyme was also inactivated by beta-iodopenicillanate. In this case, the acyl enzyme rearranged into an alpha-beta unsaturated ester and inactivation was irreversible. In contrast to the situation prevailing with the Streptomyces albus G beta-lactamase, no turn-over of beta-iodopenicillanate was observed.
authors.affiliation: Service de Microbiologie, Université de Liège, Sart Tilman, Belgium.
authors.forename: M V
authors.initials: MV
authors.lastname: Lenzini
authors.forename: J M
authors.initials: JM
authors.lastname: Frère
mesh_terms: D002440:Cefoxitin / Q000494:pharmacology*; D007700:Kinetics; D010397:Penicillanic Acid / Q000494:pharmacology* / Q000031:analogs & derivatives; D013302:Streptomyces / Q000201:enzymology*; D065093:beta-Lactamase Inhibitors
chemical_list: D065093:beta-Lactamase Inhibitors; D002440:Cefoxitin; D010397:Penicillanic Acid; C031528:6-iodopenicillanic acid