Purification of human gastric proteases by immunoadsorbents. Pepsinogen I group.

Human pepsinogen I group was purified by immunoadsorption techniques. Gastric mucosal extracts containing the pepsinogen I group and the pepsinogen II group and concentrated urine containing only pepsinogen I group were separated by DEAE-ion-exchange chromatography to remove the bulk of human serum protein. Fractions displaying proteolytic activity were further purified by adsorption on an anti-pepsinogen I group Sepharose immunoadsorbent column. After desorption, gastric pepsinogen I group was separated from pepsinogen II group. Trace amounts of contaminating protein were removed from preparations from gastric mucosal extracts and urine by passage over an anti-human serum immunoadsorbent column. The purity of pepsinogen I group from both sources was assessed by electrophoretic and immunological criteria. The isolated pepsinogen I group from gastric mucosal extracts and urine were by biochemical and immunochemical criteria identical with each other and with the pepsinogen I group in the unfractionated starting materials. By agarose enzyme electrophoresis four bands were detected and it was determined that the proteases of the pepsinogen I group express the same individual antigenic determinant.