Abstract
A simple direct spectrophotometric method for the determination of butyrylcholinesterase (EC 3.1.1.8) and arylesterase (EC 3.1.1.2) activities has been developed. New chromogenic substrates, (3-carboxypropyl) trimethylammonium iodide o-nitrophenyl ester (I) and (3-carboxypropyl) trimethylammonium iodide p-nitrophenyl ester (II), as well as new fluorogenic substrate, (3-carboxypropyl) trimethylammonium iodide 4'-methylumbelliferyl ester (III), were used in this study. Horse serum butyrylcholinesterase equally catalyzed hydrolysis of the compounds, I, II and III. Hydrolysis of these compounds by trypsin, chymotrypsin, acetylcholinesterase and carboxylesterase was negligible or quite slow. By human serum butytylcholinesterase, however, only the compound I was preferentially hydrolyzed. The compound III, by contrast, was found to be a specific substrate for arylesterase of human serum without being affected by the butyrylcholinesterase. All these measurements were carried out readily and efficiently, by analyzing highly colored products with I and II, and highly fluorescent product with III.
