Separation of pepsinogen I, pepsinogen II, and pepsinogen III from human gastric mucosa

Extracts of acidified human gastric fundic mucosa have been fractionated on diethylaminoethyl cellulose to yield three pepsin fractions, which have, in order of their elution, been attributed to pepsin I, pepsin II A, and a mixture of pepsin II B and pepsin III. Acidification of previously purified pepsinogen I and pepsinogen III yields pepsin I and pepsin III, respectively. Acidification of previously purified pepsinogen II yields two distinct pepsin fractions, pepsin II A and pepsin II B. Pepsin II B and pepsin III have the same chromatographic mobility on diethylaminoethyl cellulose, but are probably not identical. Pyloric and duodenal mucosa yield only pepsin I upon acidification. Human pepsin-pepsin inhibitor complex is demonstrable as a chromatographic fraction distinct from pepsins upon fractionation of acidified dilute pepsinogen solutions with diethylaminoethyl cellulose equilibrated with acetate buffer pH 5.3.