Abstract
Extracts of human and swine pyloric mucous membrane digest proteins with 2 pH maxima below pH 5. These maxima occur at lower pH values than the corresponding maxima for fundic extracts. Swine pyloric juice also exhibited 2 proteolytic pH maxima, at pH values 1.6 and 2.6, which are lower than those of swine or human fundic extracts of human gastric juice. Crystalline swine pepsin can be separated into two components, one of which digested proteins with pH maxima close to those found with swine fundic mucosa and the other with maxima close to those found with pyloric mucosa. It is concluded that in man and the pig there are two main pepsins, one of which predominates in the pyloric mucosa and the other in the mucosa of the fundus and body of the stomach.