title: Vitamin K-dependent carboxylase. Carboxylation of aspartyl residues to beta-carboxyaspartyl residues in synthetic substrates.
abstract: The rat liver microsomal vitamin K-dependent carboxylase has been shown to carboxylate the aspartyl residue in N alpha-t-butyloxycarbonylaspartic acid alpha-benzyl ester to a beta-carboxyaspartyl residue. The enzyme also carboxylates aspartyl residues in low molecular weight peptides to beta-carboxyaspartyl residues, but much less effectively than Glu residues in homologous peptides are carboxylated to gamma-carboxyglutamyl residues. The carboxylated product was identified by comparison to authentic beta-carboxyaspartate, by loss of 50% radioactivity incorporated from 14CO2 upon acid hydrolysis, and by identification of [14C]aspartic acid following acid hydrolysis. When peptides containing both aspartyl and glutamyl residues were used as substrates for the enzyme, the only carboxylated product detected was gamma-carboxyglutamic acid.
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives; D002250:Carbon Radioisotopes; D019735:Carbon-Carbon Ligases; D007700:Kinetics; D008025:Ligases / Q000378:metabolism*; D008862:Microsomes, Liver / Q000201:enzymology*; D009842:Oligopeptides / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D013379:Substrate Specificity
chemical_list: D002250:Carbon Radioisotopes; D009842:Oligopeptides; D001224:Aspartic Acid; C035574:t-butyloxycarbonylaspartic acid alpha-benzyl ester; D008025:Ligases; D019735:Carbon-Carbon Ligases; C020660:glutamyl carboxylase