The proteases of the common malayan toad Bufo melanostictus schneider

Abstract

1. 1. The contents of the stomach of Bufo melanostictus had acidic pH (2.2); all other segments of the digestive tract had a slightly alkaline pH (7.2-7.6). 2. 2. The pepsin-type protease had an optimum pH at 2.0-2.2 and the alkaline protease had an optimum pH at 7.2. The former responded more to the increase of temperature than the latter. 3. 3. Quantitative distributions of these two proteases were determined and compared. The alkaline protease appeared to be more important than pepsin in protein digestion. 4. 4. Effects of starvation and environmental temperature on protease secretion were also determined. © 1990.