Purification and characterization of arginine ester hydrolases from the venom of the Chinese habu snake (Trimeresurus mucrosquamatus)

An arginine ester hydrolase (ME-5) was isolated from the venom of Trimeresurus mucrosquamatus by column chromatography on Sephadex G-100, CM-Sephadex C-50, DEAE-Sephacel and by isoelectric focusing, obtaining 1.4 mg of purified enzyme from 1 g of crude venom. The enzyme was homogeneous by SDS and non SDS disc electrophoresis on polyacrylamide gel at pH 8.3. ME-5 is a glycoprotein which possesses both TAME hydrolase and capillary permeability-increasing activity, but it did not show clotting or bradykinin-releasing activities. Its molecular weight is approximately 33,000 and its isoelectric point is 6.48. The enzyme is stable to heat treatment and to pH changes between 5 and 9. Trimeresurus mucrosquamatus venom contains five arginine ester hydrolases, designated as ME-1, 2, 3, 4 and 5. Three of the five (ME-3, 4 and 5) are inactivated by DFP, suggesting that the serine hydroxyl group is involved in enzymatic activity. All five arginine ester hydrolases showed capillary permeability-increasing activity, but none of the enzymes showed clotting activity. Their amino acid compositions were determined and all appear to be unique and distinct from those of other snake venoms.