3-STAGE CHROMOGENIC ASSAY FOR THE ANALYSIS OF ACTIVATION PROPERTIES OF FACTOR-X BY CANCER PROCOAGULANT

The cysteine proteinase, cancer procoagulant (CP; EC 3.4.22.26) was is olated from human amnion-chorion and purified by precipitation with po lyethylene glycol and either ion exchange or immunoaffinity chromatogr aphy. A new, sensitive, three-stage chromogenic assay was developed fo r determination of CP factor X-activating activity. Using this assay s ome properties including dose-response, effect of calcium, phospholipi d and pH on the activation of factor X by CP were determined. There wa s an excellent linear correlation (r2 = 0.99) between concentration an d the enzymatic activity of CP. The activation of factor X by purified CP was calcium dependent with an optimum calcium concentration of 7 m M. CP was not phospholipid dependent. There was a rather broad pH opti mum between pH 6.9 and 7.25 for the activation of factor X by CP.