Partial purification of bovine liver vitamin K-dependent carboxylase by immunospecific adsorption onto antifactor X.

Administration of vitamin K-antagonists induces the appearance of abnormal clotting factors in the blood (man, cow) or in the l iver (rat). These abnormal clotting factors (descarboxyfactors) contain glutanfc acid (G1u) residues instead of the 7-carboxyglutamic acid (Gia) residues, which occur in normal clotting factors [1]. In human and bovine plasma -90% of the abnormal proteins consists of descarboxyprothrombin. Attempts to identify the rat liver abnormal proteins have been done in an in vitro vitamin K-dependent carboxylating enzyme system (carboxylase) and it was shown that only 25% ofthe carboxylated endogenous substrates bound to antiprothrombin antibodies [2]. Here, we describe the preparation of vitamin K-dependent carboxylase frorn the livers of warfarintreated cows and the results of our investigations concerning the distribution of the various clotting factor precursors in this enzyme system.