Colorimetric determination of red blood cell acetylcholinesterase activity

Abstract

Summary 1. Effects of various parameters on the production of color from 5:5-dithiobis-2-nitrobenzoate as chromogen are described. 2. Slightly higher values were obtained with the hemolysates compared to those with the whole cells. 3. The rates of reaction were linear within the concentrations of the enzyme used in the presence of a number of substrate concentrations. Maximal rate of hydrolysis was obtained at a substrate concentration of about 1.0 × 10 — mol/l. 4. The rate of hydrolysis increased linearly as the temperature of reaction medium rose from 5 to 37. 5. The pH for optimal activity was observed to be within 8 to 9. The rate of non-enzymatic hydrolysis of the substrate increases very rapidly at pH higher than 8.6. 6. The enzyme activity in borate and tris buffers was much lower compared to that in the phosphate or barbital buffers. The inhibitory effect of tris buffer was partially reversed by the presence of phosphate buffer.