摘要：

Preface factor X is a glycoprotein that plays a central role in blood coagulation. It is present in a precursor form in normal plasma, but is inactive in patients with Stuart disease. Factor X is activated by two physiological pathways called the intrinsic and extrinsic systems. In the intrinsic coagulation system, factor X is activated by factor IXa in the presence of factor VIII, phospholipid, and calcium ions. In the extrinsic system, it is activated by tissue factor and another plasma protein called factor VII. Factor X is also activated by other proteolytic enzymes, such as pancreatic trypsin and a protease from Russell's viper venom. Bovine factor X has been isolated in two different forms, factor X 1 and factor X a , which are separated by column chromatography on DEAE-Sephadex. Factor X was first isolated by Esnouf and Williams as the protein substrate for the Russell's viper venom protease. Thereafter, more efficient methods have been developed by several different groups of investigators in which the yield and quality of this protein have been improved. The use of protease inhibitors during the purification steps has been of considerable importance for the isolation of un-degraded protein in the precursor form. This chapter elaborates on the assay on determining the protein by the Biuret method using crystalline bovine serum albumin as a standard or the spectrophotometric method is employed for the homogeneous preparations using an extinction coefficient of 14.5.

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