title: Vitamin K and the biosynthesis of prothrombin. V. Gamma-carboxyglutamic acids, the vitamin K-dependent structures in prothrombin.
abstract: Tryptic peptides obtained from normal prothrombin have been compared with those obtained from prothrombin synthesized by cattle given the vitamin K antagonist dicumarol. Two peptides were found which contain vitamin K-dependent structures. These peptides contain residues 4 through 10 and residues 12 through 44, respectively. One of these (residues 4 through 10) has previously been shown to contain gamma-carboxyglutamic acid residues. Digestion of this peptide with aminopeptidase M and carboxypeptidase B yielded a tetrapeptide (residues 6 through 9). Mass spectra of this peptide showed that it has the structure Leu-Glu(CO2)-Glu(CO2)-Val. The structure of the peptide containing residues 12 through 44 was determined by automated degradation in a peptide sequenator. The modified glutamic acid residues were identified by mass spectrometric comparison with the thiohydantoin derivatives of synthetic gamma-carboxyglutamic acid. This approach unequivocally demonstrated that all of the first 10 glutamic acid residues in prothrombin are carboxylated to form gamma-carboxyglutamic acid residues. Evidence is also presented that indicates that these gamma-carboxyglutamic acid residues constitute the entire vitamin K-dependent modification of prothrombin.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000626:Aminopeptidases; D000818:Animals; D002268:Carboxypeptidases; D002417:Cattle; D002852:Chromatography, Ion Exchange; D002855:Chromatography, Thin Layer; D001728:Dicumarol / Q000494:pharmacology; D005971:Glutamates / Q000096:biosynthesis*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D009842:Oligopeptides / Q000032:analysis / Q000138:chemical synthesis; D010446:Peptide Fragments / Q000032:analysis; D011516:Prothrombin / Q000096:biosynthesis; D014357:Trypsin; D014812:Vitamin K / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D005971:Glutamates; D009842:Oligopeptides; D010446:Peptide Fragments; D014812:Vitamin K; D001728:Dicumarol; D011516:Prothrombin; D002268:Carboxypeptidases; D000626:Aminopeptidases; D014357:Trypsin