Separation and Characterization of Human Pepsinogens and Pepsins by High-Resolution Discontinuous Electrophoresis
The mucosal lining of the human stomach contains 2 immunologically distinct types of secretory zymogens, pepsinogen A (PgA) and pepsinogen C (PgC).1 The difference between the primary structure of PgA and PgC is about 50%.2,3 Both PgA and PgC consist of molecular variants that differ in net ionic charge. This heterogeneity is due to post-translational modifications (isoforms) and to differences in the primary structure (isozymogens); the latter may be about 1% within the group of PgA.4 The polymorphism in human pepsinogens and their pepsin counterparts raises the question as to whether some isoenzymes or isoforms are more mucolytic than others. Pepsin A1 (called also pepsin 1), a group of the most acidic isoforms of pepsin, displays some features5,6 suggesting that this class of pepsins is more “ulcerogenic” than others, but data are currently limited. Studies on the mucolytic properties of the individual isoenzymes and isoforms as well as a detailed examination of the secretion of each form of pepsin(ogen) within the stomach are required to give some insight into this question. To date, such studies have not been easy to undertake, since there was no suitable method for the separation and quantification of different forms of pepsin. Here, we report the multiphasic buffer systems that create a low pH during discontinuous electrophoresis in Polyacrylamide gels. These electrophoretic systems “stack” and separate pepsinogens and pepsins at pH close to their pI values, exhibiting a high resolving power for these proteins.
KeywordsMucosal Lining Human Gastric Juice Chronic Peptic Ulceration Acidic Isoforms Electrophoretic System
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