A protease from tomato flesh was purified to homogeneity by (NH4)2SO4 precipitation followed by Sephadex G-75 and DEAE-cellulose column chromatography. Molecular weight of the enzyme was estimated to be 81-79 KD by gel filtration and SDS-PAGE respectively. The enzyme was found to be a single polypeptide chain as revealed by SDS-PAGE under either reducing or non-reducing conditions. Optimum activity was observed at pH 7.0 and 45°C with a km value of 0.48 per cent determined by using casein as substrate. The enzyme appears to be a serine protease being inhibited greatly by DFP and PMSF and to a lesser extent by heavy metals such as Pb2+ and Fe2+.
M.R. Karim, M.A. Islam , N. Absar and F. Hashinaga , 1999. Purification and Partial Characterization of a Protease from Tomato
(Lycopersicon esculentum Mill). Pakistan Journal of Biological Sciences, 2: 955-959.