title: [3H]diborane reduction of vitamin K-dependent calcium-binding proteins. Identification of a unique amino acid.
abstract: gamma-Carboxyglutamic acid has recently been identified as a component of the vitamin K-dependent region of bovine prothrombin (Nelsestuen, G. L., Zytkovicz, T. H., and Howard J. B. (1974) J. Biol Chem. 249, 6347-6350). The presence of this amino acid has been substantiated here by the reduction of vitamin K-dependent proteins with [3H]-DIBORANE. The reduction product of gamma-carboxyglutamic acid, 5,5'-[3H]dihydroxyleucine, was shown to be present in hydrolysates of reduced rat prothrombin, bovine prothrombin, and bovine factor X. The results are consistent with a minimum of 10 gamma-carboxyglutamic acid residues in the nonthrombin-generating region of bovine prothrombin but no such residues in the thrombin precursor portion of prothrombin. It is concluded that amino acid analyses of [3H]diborane-reduced proteins provides a sensitive, qualitative method for the identification of proteins which contain gamma-carboxyglutamic acid and are vitamin K-dependent.
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D001665:Binding Sites; D001880:Boranes; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D005170:Factor X / Q000378:metabolism; D013058:Mass Spectrometry; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D011516:Prothrombin / Q000378:metabolism; D051381:Rats; D014233:Tricarboxylic Acids / Q000032:analysis; D014316:Tritium; D014357:Trypsin; D014812:Vitamin K / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D001880:Boranes; D010446:Peptide Fragments; D014233:Tricarboxylic Acids; D014316:Tritium; D014812:Vitamin K; D011516:Prothrombin; D005170:Factor X; D014357:Trypsin; D002118:Calcium