Carrageenans and the proteolytic activity of human gastric secretion

Abstract The inhibition of the peptic activity of human gastric secretion by undegraded and degraded carrageenans of similar sulphate content has been examined over the pH range 1.5–3.75. Inhibition by degraded carrageenan is constant throughout this range, but inhibition by undegraded carrageenan decreases between pH 2.5 and 3.25, when a lower level is established. The inhibition by both types of carrageenan is caused by substrate-inhibitor interaction. The differences in degree of inhibition and the effect of pH on the inhibition by undegraded carrageenan appear to originate in the differing natures of the substrate-inhibitor complexes formed by degraded and undegraded carrageenans.