title: Vitamin K-dependent carboxylase. Development of a peptide substrate.
abstract: Rat liver microsomes contain a vitamin K-dependent carboxylase activity that converts specific glutamyl residues of microsomal prothrombin precursor to gamma-carboxyglutamic acid residues. This activity has now been solubilized by treatment with Triton X-100. The pentapeptide, Phe-Leu-Glu-Glu-Val, has been synthesized; and it has been demonstrated that, in the presence of this peptide, the solubilized microsomes catalyze a vitamin K-dependent incorporation of added H14CO3- into a low molecular weight trichloroacetic acid-soluble compound. The carboxylated product has been identified as peptide-bound gamma-carboxyglutamic acid by its chemical stability during acidic and alkaline hydrolysis and by co-chromatography of an alkaline hydrolysate of the product with authentic gamma-carboxyglutamic acid. The conditions for peptide carboxylation appear to be identical with those demonstrated for precursor carboxylation.
mesh_terms: D000818:Animals; D002262:Carboxy-Lyases / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D009842:Oligopeptides / Q000138:chemical synthesis; D051381:Rats; D014812:Vitamin K / Q000494:pharmacology*; D014813:Vitamin K Deficiency / Q000201:enzymology*
chemical_list: D009842:Oligopeptides; D014812:Vitamin K; D002262:Carboxy-Lyases