Effect of Sulfate Content of Several Anionic Polymers on in Vitro Activity of Pepsin

Carrageenan was degraded with acid to give materials with sulfate contents varying from 5–30%. Antipeptic activities of these materials correlated closely with the sulfate content. Other sulfated polymers such as polyvinyl sulfonate, sulfated rice starch, amylose sulfate, heparin, etc., gave a similar correlation. All these polymers precipitated protein in the antipeptic test. Compounds such as sodium lauryl sulfate and m-xylene sulfonate possessed significant antipeptic activity but did not precipitate protein, and no correlation between sulfate content and antipeptic activity was found. The precipitation of protein by carrageenan depends upon the pH, becoming negligible at a pH above 4.5.