The localization of a vitamin K-induced modification in an N-terminal fragment of human prothrombin.
1. The N-terminal fragment (PF-I) split off from prothrombin during coagulation was purified to homogeneity from human serum. 2. The apparent molecular weight is 27000+/-2000 in sodium dodecyl sulphate-polyacrylamide-gel electrophoresis, whereas a value of about 19600 is obtained by calculation based on amino acid and carbohydrate analyses. The N-terminal sequence is an Ala-Asx bond. The fragment contains about 16% carbohydrate, binds phospholipids in the presence of Ca(2+) and is adsorbed to BaSO(4). The pK(a) of its BaSO(4)-binding group(s) is 3.1-3.5. 3. By CNBr cleavage of fragment PF-I two peptides (C-1 and C-2) were obtained with molecular weights of about 5900 (C-2) and 12400 (C-1) on the basis of amino acid and carbohydrate analyses. Only the smaller (N-terminal) peptide is adsorbed to BaSO(4) and, since the ability of the whole protein to bind to BaSO(4) is known to be absent in samples obtained from patients treated with vitamin K antagonists, this peptide probably contains the site of a modification to the structure of the protein which occurs during biosynthesis and depends on vitamin K. This peptide does not contain hexosamine or sialic acid.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001466:Barium Sulfate; D001780:Blood Coagulation Tests; D002118:Calcium; D002241:Carbohydrates / Q000032:analysis; D002268:Carboxypeptidases; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007106:Immune Sera; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007158:Immunologic Techniques; D007700:Kinetics; D008970:Molecular Weight; D010743:Phospholipids; D011485:Protein Binding; D011506:Proteins / Q000032:analysis; D011516:Prothrombin / Q000302:isolation & purification*; D011817:Rabbits / Q000276:immunology; D014812:Vitamin K / Q000494:pharmacology*
D000596:Amino Acids; D002241:Carbohydrates; D007106:Immune Sera; D010743:Phospholipids; D011506:Proteins; D014812:Vitamin K; D001466:Barium Sulfate; D011516:Prothrombin; D002268:Carboxypeptidases; D002118:Calcium