A new vitamin K-dependent protein. Purification from bovine plasma and preliminary characterization.

TLDR

Four coagulation factors (II, VII, IX, X) require vitamin K for biosynthesis, and a previously unrecognized vitamin K‑dependent glycoprotein was purified from bovine plasma, though its biological function remains unknown. The study aimed to purify and characterize this novel vitamin K‑dependent glycoprotein from bovine plasma. The protein was characterized as a ~56,000‑Da glycoprotein with two polypeptide chains, similar to factor X. Dicoumarol interferes with its biosynthesis, its light chain binds Ca²⁺, and its N‑terminal sequence is homologous to other vitamin K‑dependent proteins and contains γ‑carboxyglutamic acid residues.

Abstract

Four proteins active in blood coagulation have long been known to require vitamin K for their proper biosynthesis: factors II, VII, IX, and X. This paper describes the purification of a hitherto unrecognized vitamin K-dependent glycoprotein from bovine plasma. The biosynthesis of this protein is interfered with by the vitamin K antagonist Dicoumarol. The molecular weight of the protein is approximately 56,000 and, like factor X, it has two polypeptide chains. The light chain binds Ca2+. Its NH2-terminal amino acid sequence is homologous to the NH2-terminal sequences of the other vitamin K-dependent proteins and it contains vitamin K-dependent gamma-carboxyglutamic acid residues. The biological function of this protein is unknown.