The pH dependence of lipase and trypsin activity

We investigated in-vitro the relation of the lipase and trypsin activity, containing in native duodenale juice, to pH-values, similar to them registered in the duodenum of patients with severe exocrine insufficiency. Therefore week alcaline duodenal juice was acidified by native gastric juice or hydrochloric acid to pH-value 7, 6, 5 und 4. The remaining activity was estimated after 5, 10, 15 and 20 minutes. We determined a fast inactivation of lipase at pH 5.0 or below (incubation of 5 minutes only decreased the activity to 35% of origin), and of trypsin at pH 4.0 or below (incubation of 5 minutes at this pH-value decreased the activity to 26% of origin). According to the denaturating effect on the enzymes, there was no difference between gastric juice and hypochloric acid. It is concluded, that the activity of decreased secreted pancreatic enzymes in severe exocrine pancreatic insufficiency and also of the oral substituted enzymes is additionally reduced by acidic duodenal circumstances, so that a gastric acid neutralizing or inhibiting therapy proves as necessary.