Proteolytic activity of Oidiodendron kalrai

Abstract

The physiochemical characteristics of the intracellular proteolytic enzymes of Oidiodendron kalrai, a neuropathogenic fungus, were studied. The organism in the yeast phase was grown in a semisynthetic medium containing 1% tryptone, at 37 °C for 48 h, on a gyrotory shaker. The crude extract was prepared by breaking the cells in a French pressure cell and the proteolytic activity was tested against biological substrates. The cell-free extract hydrolyzed casein, hemoglobin, lactalbumin, gelatin, elastin, collagen, and purified rabbit renal basement membrane to various degrees. Optimal proteolytic activity was observed at pH 6 and at 32 °C. Calcium and EDTA did not affect the enzymatic activity; however, activity was partially inhibited by sulfhydryl-blocking agents and by heat-inactivated horse, calf, and human serum. The extract was totally inactivated by exposure to a temperature of 70 °C for 60 min. Storage at −76 °C or −15 °C for 6 months or at 4 °C for 4 weeks did not affect protease activity.