title: Purification and characterization of an imipenem hydrolysing metallo-beta-lactamase from Bacteroides fragilis.
abstract: An imipenem resistant beta-lactamase producing strain of Bacteroides fragilis was isolated from a clinical specimen. The specific activity of the unpurified beta-lactamase was 5.5 U/mg protein. The beta-lactamase was purified 60-fold by Q Sepharose, Sephacryl S-300 and Mono Q column passages. The strain was able to inactivate imipenem and cefoxitin in broth cultures. The enzyme hydrolysed imipenem more rapidly than ampicillin, benzylpenicillin, cephalothin and cefoxitin. The activity of the enzyme was Zn2+ dependent and was completely inhibited by EDTA. The inhibition was reversed by ZnSO4. Preincubation with the common beta-lactamase inhibitors clavulanic acid, sulbactam and tazobactam did not reduce the enzyme activity. The molecular weight was determined by sodium dodecyl sulfate gradient gel electrophoresis to be 31,000 Daltons and the isoelectric point was 4.5.
authors.affiliation: Department of Microbiology, Huddinge University Hospital, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Hedberg
authors.forename: C
authors.initials: C
authors.lastname: Edlund
authors.forename: L
authors.initials: L
authors.lastname: Lindqvist
authors.forename: M
authors.initials: M
authors.lastname: Rylander
authors.forename: C E
authors.initials: CE
authors.lastname: Nord
mesh_terms: D001441:Bacteroides fragilis / Q000187:drug effects / Q000201:enzymology*; D001711:Biotransformation; D002440:Cefoxitin / Q000493:pharmacokinetics; D002511:Cephalosporins / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D015378:Imipenem / Q000378:metabolism* / Q000493:pharmacokinetics; D007526:Isoelectric Point; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D008970:Molecular Weight; D010406:Penicillins / Q000378:metabolism; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D002511:Cephalosporins; D010406:Penicillins; D065093:beta-Lactamase Inhibitors; D002440:Cefoxitin; D015378:Imipenem; D004492:Edetic Acid; D001618:beta-Lactamases