RESUMO
Protease isolated from Ascaris was characterized and its effect on blood clotting factors and platelets was studied. It was purified to homogeneity from the homogenate of Ascaris summ by 2 steps of fractionation using Sephadex G100 and DEAE-Sepnadex A50. The molecular weight of the enzyme was about 37,000 as determined by SDS- PAGE. It had an isoelectric point [pI] of 6.3. Using casein as a substrate, it had a Km of 1.9 mg, optimal temperature of 37C and optimal pH of 6. It had no carbohydrate content. The enzyme activity was completely inhibited by iodoacetamide suggesting that it is sulfhydryl protease. The activity was partially inhibited by Ca ++, Co ++, Ba + and benzamedine, while it was not effected by EDTA, DFP, beta-mercaptoethanol, Mg ++ or Mn ++. The purified enzyme had no effect on plasma recalcification time or fibrinogen clotting time. It also had no effect on activation of human platelets or even on the aggregation induced by ADP. The isolated protease may be used in serodiagnostic, chemotherapeutic or immunological intervention