title: The kinetics of CAZ-5, a novel SHV-related plasmid-mediated beta-lactamase with enhanced hydrolytic activity against ceftazidime.
abstract: The kinetic constants for "CAZ-5", a novel plasmid-mediated beta-lactamase with noticeable activity against third-generation cephalosporins and particularly ceftazidime have been determined. Two closely-related plasmid-mediated beta-lactamases have also been studied: SHV-2 and PIT-2 (also known as SHV-1). These enzymes were synthesized constitutively; they were highly sensitive to the action of the inhibitors clavulanic acid and sulbactam and they lacked activity against the cephamycins and imipenem. PIT-2/SHV-1 had poor hydrolytic activity against the third-generation cephalosporins, SHV-2 was markedly active against cefotaxime and related compounds, whereas the new enzyme, which was also active against these cephalosporins, had a noticeably greater activity against ceftazidime. Aztreonam was slowly hydrolysed by CAZ-5 beta-lactamase, but demonstrated an unusually high affinity for this enzyme.
authors.affiliation: National Museum of Natural History, UA 401 CNRS, Paris, France.
authors.forename: R
authors.initials: R
authors.lastname: Labia
authors.forename: A
authors.initials: A
authors.lastname: Thabaut
authors.forename: A
authors.initials: A
authors.lastname: Morand
authors.forename: K
authors.initials: K
authors.lastname: Tiwari
authors.forename: D
authors.initials: D
authors.lastname: Sirot
authors.forename: J
authors.initials: J
authors.lastname: Sirot
mesh_terms: D002442:Ceftazidime / Q000378:metabolism*; D002511:Cephalosporins / Q000378:metabolism; D002513:Cephamycins / Q000378:metabolism; D006868:Hydrolysis; D015378:Imipenem / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics; D010957:Plasmids; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D002511:Cephalosporins; D002513:Cephamycins; D007527:Isoenzymes; D015378:Imipenem; D002442:Ceftazidime; C062759:beta-lactamase CAZ-5; C054882:beta-lactamase PIT-2; C062760:beta-lactamase SHV-2; D001618:beta-Lactamases