Rapid qualitative protease microassay (RPM)

A rapid qualitative protease microassay (RPM) was developed as an alternative to conventional assays of cysteine protease activity in HPLC fractions. Using this technique protease activity in samples could be visually determined within 5 min. The method was sensitive to 3.3 × 10− 7 U/mL of papain and detected cysteine protease activity in dilute HPLC fractions with activity of 5.4 × 10− 5 U/mL. Because the method monitors the decolorization of Coomassie Brilliant Blue stained substrate, it can be modified to detect other classes of proteases.