Abstract

The present study provides plant-derived extracts to characterize the activity and kinetics of protease enzymes of Mentha piperita L and Thymus capitatus L. The results illustrated that these crude extracts have a proteolytic activity within optimum pH (3–9) and optimum temperature (35–50°C). The study of the ionizable groups in or around the active site of these proteases by Dixon-Webb’s plot reveals the occurrences or the presence of aspartic acid with pKa1 at pH 2.9 and pKa2 at pH 3.2, and cysteine amino acids in or around the active site with pKa1 at pH 6.7 and pKa2 at pH 7.2; interestingly, these proteases maybe belonged to the acid proteases and neutral proteases. Enzymatic kinetics studies (km, Vmax, Vmax/km) indicated that egg albumin is a good substrate for proteases of M. piperita L. and T. capitatus L.

Key words: Kinetic parameters, Protease enzyme, Thyme, Mentha, Ionizable groups.