title: Carboxy groups as essential residues in beta-lactamases.
abstract: Beta-lactamases are divided into classes A, B and C on the basis of their amino acid sequences. Beta-Lactamases were incubated at pH 4.0 with the carboxy-group reagent 1-(3-dimethylaminopropyl)-3-ethylcarbodi-imide plus a coloured nucleophile and the extents of inactivation and nucleophile incorporation were monitored. Two class A enzymes (from Bacillus cereus and Bacillus licheniformis) and two class C enzymes (from Enterobacter cloacae P99 and Pseudomonas aeruginosa) were examined. All four enzymes were inactivated, with total inactivation corresponding to the incorporation of approx. 2-3 mol of nucleophile/mol of enzyme. In the case of beta-lactamase I from Bacillus cereus, some 53% of the incorporated nucleophile was located on glutamic acid-168 in the amino acid sequence.
mesh_terms: D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000494:pharmacology; D005029:Ethylenediamines / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D005029:Ethylenediamines; D007527:Isoenzymes; D010446:Peptide Fragments; D065093:beta-Lactamase Inhibitors; C026951:N-(2,4-dinitrophenyl)ethylenediamine; D001618:beta-Lactamases; D005022:Ethyldimethylaminopropyl Carbodiimide