Gastric Juice Ii. Studies on a Urea-splitting Enzyme and Pepsin in Relation to the Proteins

It has been shown that a urea-splitting enzyme is present in normal gastric juice (1). Its range of activity was at least hetween pH 1.4 and 8.3, and its greatest action was found to take place at pH 7.8. Its activity was slow, and continued over a space of several days; the greatest part had taken place by the end of the first 24 hours. Owing to these characteristics it was suggested that the enzyme was probably different from that isolated and crystallized from the soy bean by Sumner (2). In connection with the studies described in Paper I (3), it became of interest to determine to which of the two protein or protein-like substances of the gastric juice the urea-splitting enzyme and pepsin were attached.