Purification and properties of human coagulation factor VII.

Abstract

Blood coagulation Factor VII was purified 100,000-fold from fresh frozen human plasma to apparent homogeneity with a yield of 30% based on coagulation assay. The molecular weight estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 48,000. Factor VII is composed of a single polypeptide chain with the NH2-terminal sequence Ala-Asn-Ala-Phe-Leu-(Gla)-(Gla)-Leu-(Arg)-Pro. It is converted to a two-chain form (Factor VIIa) connected by disulfide bonds by the action of Factor Xa, in the presence of phospholipids and calcium, and by Factor XIIa without additional cofactors. This conversion is associated with a 20- to 25-fold increase in coagulation assay activity. Factors VII and VIIa were inhibited by 15 mM diisopropyl fluorophosphate with 50% inactivation in 160 and 60 min, respectively. The presence of tissue factor and CaCl2 accelerated the inactivation by approximated 5-fold. Neither Factor VII nor VIIa were inhibited by antithrombin III in the absence of heparin. However, with the addition of heparin, Factor VIIa was inhibited at a rate approximately 25 times that of Factor VII.