Dual-substrate plate diffusion assay for proteases

Abstract

A plate diffusion assay for endopeptidases was developed. Proteases applied to plates containing 1% casein, 1% gelatin, and 1.5% agar caused distinct zones reminiscent of immunoprecipitation bands. The diameter of the zones was linearly proportional to the log of the enzyme activity applied over a range from 0.01 to greater than 100 IU/ml.