Enzymochemical studies on snake venoms. X. Purification and properties of arginine ester hydrolase (ME-3) in the venom of Trimeresurus mucrosquamatus

Abstract

One of the TAME hydrolases of Trimeresurus mucrosquamatus venom was isolated by a combination of gel filtration on Sephadex G-100 and ion exchange chromatographies on CM-Sephadex C-50, Aminohexyl-Sepharose 4B and DEAE-Sephacel. From 1 g of the lyophilized venom 1.5 mg of purified arginine ester hydrolase was obtained. The substrate specificity of this enzyme was strictly directed to the hydrolysis of ester linkages to which an arginine residue contributed the carbonyl group. The esterolytic activity was inhibited by benzamidine, N-(p-tosyl)-L-phenylalanine chloromethyl ketone (TPCK) or diisopropyl fluorophosphate (DFP). The purified enzyme was proved to be homogeneous by electrophoresis on polyacrylamide gel and isoelectric focusing. The molecular weight was found to be about 33000. Its isoelectric point was 6.93. The esterolytic activity of the final preparation was 125.7 unit/mg. This enzyme had capillary permeability-increasing activity, but not kininreleasing and clotting activities. This protein was stable to heat treatment, and between pH 4-9. Its Michaelis constant (Km) for TAME and inhibition constants (K1) for benzamidine, TPCK, and DFP were found to be 7.81×10-3 M, 0.67×10-3 M, 0.43×10-3 M, and 3.66×10-3 M, respectively. This enzyme was a glycoprotein.