[Do ulcerogenic pepsins exist? Characterization of polymorphism of human pepsins]

Studies on the role of pepsin in the pathogenesis of peptic ulcer are hampered by lack of suitable methods for the separation, characterization and quantification of different forms of pepsin. As a contribution toward solving this problem, we have developed several electrophoretic systems which exhibit a high resolving power for pepsins and their precursors, pepsinogens. When human gastric juices were fractionated by discontinuous electrophoresis at pH 3.7 in polyacrylamide gel, pepsin was resolved into as many as 20 distinct forms: 3 major isoenzymes (C, A4, A3), 4 less abundant isoforms (C', A6, A4', A3' or A2), 8-10 minor isoforms of pepsin A1 and at least 3 dimeric isoforms of pepsin A (Ad). All the pepsin components were identified by means of bidimensional electrophoresis. Pepsinogens from gastric mucosa were separated by discontinuous electrophoresis at pH 5.5 in the first dimension, then converted to pepsins in the gel by acidification and resolved by electrophoresis at pH 3.7 in the second dimension. Based on discontinuous electrophoresis at low pH, a much needed method was elaborated for the quantification of different forms of pepsin(ogen) within the stomach. This technique will allow detailed clinical studies which may provide insight into the question whether or not there are specific forms of pepsin that are associated with peptic ulcer.