[A method of serial determination of calpain activity in biological material]

A procedure for quantitatively estimating the activity of calpains involved chromatography on the hydrophobic sorbent octyl-Sepharose CL-4B, which enabled one to measure the true proteinase activity unmasked by the inhibitors calpastatins. After binding with the sorbent and removal of the contaminating proteins the calpains were eluted using 0.5% sodium cholate as well as by an increase of pH value from 7.0 to 8.0 and by a decrease of the buffer ionic strength. Activity of the calpains was estimated using casein as a substrate in mice heart, liver and skeletal muscle, in rat and human erythrocytes. Simple and rapid technique of enzymatic activity estimation allowed one to use the procedure developed in the laboratory and clinical settings and to carry out serial measurement of the activity in small quantities of the material.