Low molecular weight serine protease has been purified from the seeds of Holarrhena antidysenterica to electrophoresis homogeneity by the combination of size exclusion and ion exchange chromatography. The molecular mass was estimated by SDS-PAGE to be about 25 kDa. The enzyme showed optimum activity at pH 7.5 and exhibited its highest activity at 35°C using 1% casein as a substrate. The enzyme was strongly inhibited by 2 mM PMSF but not by EDTA and cysteine protease inhibitors, suggesting the presence of serine residues at the active site. The enzyme had a Km of 1.1 mg mL-1 and Vmax of 389.71 units min-1 mg-1 of protein.
