Abstract
The activities of proteolysis and coagulation of gastric juices and extracts from the suckling infant were examined to ascertain whether rennin was secreted in the infant stomach or not. Their catheptic action was also studied.
1. Rennin retained its coagulability in more alkaline medium than pepsin. This fact cannot be utilized, however, to discriminate those enzymes in the stomach, because there are different activities even in the preparations of each enzyme.
2. There was no difference in the degree of inhibition by acetone between the two enzymes. By the action of horse or ox serum, the coagulability of pepsin was much more inhibited than that of rennin, but this method was not suitable for discrimination of the two enzymes, because it was difficult to obtain exact results.
3. Gastric juices from infants had strong proteolytic activity. In this point, they we different from rennin and were as strong as, or stronger than, pepsin.
4. From the pH-activity curves of those enzymes, it was made clea that 70 rennin existed and pepsin (and/or cathepsis) was an important enzyme in the infant stomach. Pepsin of the infant stomach had a more extensive pH limit than that of theswine stomach. Pepsin of the horse stomach and that of the sheep stomach had the same activity curves as that of the swine stomach.
