Characterization of a metalloprotease from psychrophilic Xanthomonas maltophilia

Abstract

An extracellular protease from psychrophilic Xanthomonas maltophilia isolated from alpine environment was purified and characterized. In spite of a comparable growth at 10°C and 20°C, protease excretion occured only at 10°C. The enzyme was a 21-kDa protein with an isoelectric point higher than 9.5. The optimum pH and temperature for azocaseinolytic activity were 8.0 and 50°C respectively. The enzyme was stable up to 40°C but became inactive after 10 min at 60°C. The energy of activation was comparable to that of enzymes from mesophilic sources. Sensitivity to EDTA indicates that X. maltophilia protease is a metalloprotease.