Abstract A proteinase secreted by Trichoderma koningii ( local isolate) was purified to apparent homogeneity by ion exchange, gel permeation, and affinity chromatography. The enzyme was optimally active at pH 10.5 and 50°C and had a PI of 9.0. It contained 16% carbohydrate, composed of 2.57% rhamnose, 8.24% arabinose, 4.22% xylose, and 1.42% galactose and was rich in glycine, serine, alanine, and aspartic acid residues. Glycine was found at the N-terminus and serine appeared to be at the active site. Fe 2+, Co 2+, and Ca 2+ at 1 m m level enhanced catalysis by 3.0-, 2.5-, and 1.7-fold. K +, Na +, Ag +, and Pb 2+ inhibited enzyme activity, while Cu 2+ and Hg 2+ at 1 m m level were not significantly inhibitory .