A CONTINUOUS METHOD FOR MEASURING CALPAIN ACTIVITY

A simplified methodology for assaying the caseinolysis by calpains was developed. This methodology, including the incubation of calpain with casein and direct measurement of the absorbance at 500 nm, is based o n the turbidity of the reaction mixture caused by the aggregation of h ydrolysates during the reaction. Unlike the typical caseinolysis assay , this novel assay does not need to separate the substrate from hydrol ysates and can be continuously monitored in visible wavelength range. The activity of calpain is expressed by the maximum reaction velocity (Delta A(500)/min) at 25 degrees C. (C) 1997 Academic Press