Isolation And Purification Of A Protein C-activating Frac-tion From Gloydius Ussurisis Venom And The Research Of Its Properties

This study was performed to establish an efficient method of isolating a ProteinC-activating fraction from Gloydius Ussurisis venom , study its biological propertiesand investigate its mechanism of Protein C activation.By means of DEAE-Sepharose FF l and Heparias-SepliaoseC column chromatography,the fraction S-PCA with Protein C-activating activity was isolaced and purified to homogeneity from the crude venom of Gloydius Ussurisis. S-PCA, which was tested by SDS-PAGE, was homogeneous, and consisted of a singlechain polypeptide with an apparent molecule weight of 18,500. Several experimentswere carried out to investigate S-PCA's mechanism of protein c activation. We estimated that S-PCA was firstly conttected with the heavy chain of protein c, formed S-PCA complex with protein c and then caused proteolytic activation.S-PCA's anticoagulant and amidolytic activity was inhibited by serine protease inhibitor PMSF and Soybean Trypsin Inhibitor STI .The metalloprotease inhibitor EDTA and plasmin inhibitor EACA had no apparent effect on the activity of S-PCA .It revealed that S-PCA was a serine protease. The pH-optimum for the action of S-PCA was 6.0-7.0. The temperature-optimum for the action of S-PCA was 38-40℃.This study presents an efficient method of separating S-PCA,and investigates itsphysiochemical properties,biological properties and functional mechanism.