pH stability and activity curves of pepsin with special reference to their clinical importance.

The concept of peptic ulceration and its treatment is based on the ulcerogenic action of acid and pepsin (Card, 1952). It appears that pepsin plays the predominant role in this action (Schiffrin, 1940; Schiffrin and Warren, 1942; Le Veen, 1947), the acid merely providing the correct pH for optimal peptic activity. Consequently, it is of some importance to know the effect ofpH on the peptic activity of pepsin. One of these effects, the effect of pH on peptic activity, has been adequately studied (Christensen, 1955; Taylor, 1959a, b and c); the effect ofpH on enzyme stability has received little attention apart from the observations of Langley in the last century (Langley, 1881a and b) and those of Northrop, Kunitz, and Herriott (1948). As both of these effects are of considerable importance in clinical gastroenterology, the present study was undertaken of the effect ofpH on the stability and activity of pepsin.