Human Serum Cholinesterase: I. Partial Purification and Nature of the Heterogeneity of this System

Abstract

Summary 1. Human serum cholinesterase (EC 3.1.1.8) was purified about 500 times from reconstituted outdated plasma by (NH4)2SO4 acid precipitation and chromatography on DEAE-cellulose. The yield was 45%. 2. The enzyme system showed seven major components on polyacrylamide gel electrophoresis, six of which survived the purification procedure and these were reduced in number to asingle rather diffuse component following prolonged treatment with neuraminidase (EC 3.2.1.18). Gel electrophoresis suggested that the five fastest components differed in size, but that aggregation of the fastest component to give different polymers of the enzyme was not a reasonable explanation of the heterogeneity. N-Acetylneuraminic acid plays an important role in maintaining the stability of this multicomponent system. 3. A tentative suggestion for the gross structure of the pseudocholinesterase molecule has been suggested.