Purification and characterization of a carboxylesterase from the latex of Synadenium grantii Hook, 'f'

摘要

The latex of S. arantii was found to contain esterolytic activity. PAGE coupled with substrate and inhibitor specificity studies revealed the presence of multiple forms of carboxylesterases and cholinesterases in the latex. One of the carboxylesterases of the latex was purified by acetone fractionation, CM-​Sephadex chromatog., and Sepharose-​6B gel filtration. The homogeneity of the enzyme was established by PAGE, isoelec. focusing, and SDS-​PAGE. The enzyme consisted of a single polypeptide chain with a mol. wt. of 14,​000. The amino acid anal. of the purified enzyme revealed that it contained a greater no. of neutral and acidic, compared to basic amino acid residues. The pI of the enzyme was 4.0. The enzyme was a glycoprotein as revealed by the periodic acid-​Schiff-​staining technique. Studies with different organophosphate and carbamate inhibitors showed that this enzyme was sensitive to organophosphates. The product inhibition studies with this enzyme showed linear competitive inhibition with acetate and linear noncompetitive inhibition with 1-​naphthol.