Camel Pancreatic Carboxylesterase. Purification and Properties

摘要

Carboxylesterase EII from camel pancreas was purified by ammonium sulphate precipitation, chromatography on DEAE-Sepharose and gel filtration on a Sepharose 6B. The purified enzyme appeared as a single protein band on native polyacrylamide gel electrophoresis. The molecular mass of esterase EII was 50,000 for the native enzyme using gel filtration. A single protein band corresponding to molecular weight 50,000 was obtained by SDS-polyacrylamide gel electrophoresis. Esterase EII had a Km value of 7.6 mM p-nitrophenyl acetate. Varying esterase activities were detected when supplied with various p-nitrophenyl-, α-naphthyl- and β-naphthyl-esters. Esterase EII had a pH optimum of 7.5. The enzyme was inhibited by Ca~(2+), Hg~(2+), Mg~(2+), and Ni~(2+) but not inhibited by Cd~(2+). Iodoacetamide, N-ethylmaleimide, p-CMB, and DTNB did not show any inhibitory effect on the hydrolyzing capacity of esterase EII. Further, esterase EII was found to be inhibited by PMSF indicating the presence of serine residue in the active site of the enzyme.