title: The beta-lactamase of Enterobacter cloacae P99. Chemical properties, N-terminal sequence and interaction with 6 beta-halogenopenicillanates.
abstract: The beta-lactamase of Enterobacter cloacae P99 consists of one polypeptide chain of Mr 39000 devoid of disulphide bridges and free thiol groups. It contains an unusually high proportion of tyrosine and tryptophan. The N-terminal sequence exhibits overlaps with the tryptic peptide obtained after labelling the active site with 6 beta-iodopenicillanate. The active-site serine residue is at position 64. The homology with the chromosomal beta-lactamase of Escherichia coli K 12 (ampC gene) is lower within the 25 residues of the N-terminal portion than around the active-site serine residue. The P99 beta-lactamase is inactivated by 6 beta-bromo- and 6 beta-iodo-penicillanate, with a second-order rate constant of 110-140M-1 X s-1 at 30 degrees C and pH 7.0, a value that is much lower than that observed with class-A beta-lactamases.
authors.forename: B
authors.initials: B
authors.lastname: Joris
authors.forename: F
authors.initials: F
authors.lastname: De Meester
authors.forename: M
authors.initials: M
authors.lastname: Galleni
authors.forename: G
authors.initials: G
authors.lastname: Reckinger
authors.forename: J
authors.initials: J
authors.lastname: Coyette
authors.forename: J M
authors.initials: JM
authors.lastname: Frere
authors.forename: J
authors.initials: J
authors.lastname: Van Beeumen
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D004754:Enterobacter / Q000201:enzymology*; D004755:Enterobacteriaceae / Q000201:enzymology*; D007700:Kinetics; D010397:Penicillanic Acid / Q000378:metabolism* / Q000031:analogs & derivatives; D013053:Spectrophotometry; D014364:Tryptophan / Q000032:analysis; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases
chemical_list: D000596:Amino Acids; D065093:beta-Lactamase Inhibitors; C018008:brobactam; D010397:Penicillanic Acid; D014364:Tryptophan; C031528:6-iodopenicillanic acid; D001618:beta-Lactamases