title: LD-carboxypeptidase activity in Escherichia coli. II. Isolation, purification and characterization of the enzyme from E. coli K 12.
abstract: A LD-carboxypeptidase from Escherichia coli K 12 was isolated by Tris-EDTA treatment and purified to electrophoretic homogeneity by DEAE-cellulose chromatography. The enzyme has a molecular weight of approximately 12,000 as determined by sodium dodecyl sulfate-polyacrylamide electrophoresis and by Sephadex G-100 gel filtration. The studies of the substrate specificity of the enzyme revealed that UDP-MurNAc-tetrapeptide is a superior substrate, with a Km value of 1 X 10(-4) mol/l. The activity of the LD-carboxypeptidase was inhibited by D-amino acids and the beta-lactam antibiotic nocardicin A. Ki values of 0.3 and 43 mmol/l were determined for nocardicin A and D-homoserine, respectively. The properties of the purified enzyme correspond to activity I in ether treated cells.
mesh_terms: D000596:Amino Acids / Q000378:metabolism / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D007769:Lactams; D008970:Molecular Weight; D010457:Peptidoglycan / Q000378:metabolism; D013379:Substrate Specificity; D014538:Uridine Diphosphate N-Acetylmuramic Acid / Q000378:metabolism
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D007769:Lactams; D010457:Peptidoglycan; D014538:Uridine Diphosphate N-Acetylmuramic Acid; C027318:nocardicin; D002268:Carboxypeptidases; C021505:LD-carboxypeptidase