High Molecular Weight Protease in Rumen Ciliate Protozoa

Abstract

Mixed rumen ciliate protozoa (mainly Entodiniinae) from goats have two kinds of protease ; one has a pH optimum of 3.0, the other is active at neutral or alkaline pH. The protease active at neutral or alkaline pH was partially purified from the supernatant after centrifugation of sonicated mixed rumen ciliate protozoa. The supernatant was chromatographed on Bio-Gel A-1.5 m and a partially purified protease was obtained. This protease had a molecular weight of more than 400, 000. When the sonicated protozoa were heated at 55°C for 15 min, the active peak from the Bio-Gel A-1.5 m column was shifted to a lower molecular weight, 27, 000. The high molecular weight protease was strongly activated by high temprature and SDS, and inhibited by E-64 c. The protease degraded many proteins including those found in rumen bacteria. These findings suggest that rumen ciliate protozoa have high molecular weight protease that plays a role in the digestion of feed and bacterial protein.