Original Enzyme Activity Research Articles

“Activator-competitive” enzyme inhibition. Interrelation of dissociation, activation, inhibition and surface inactivation of β-glucuronidase

1. 1. Dilution of β-glucuronidase causes reversible dissociation of the enzyme into inactive polypeptides. 2. 2. Many polycations are able to prevent the dissociation and, thus, act as activators of the diluted enzyme. 3. 3. Polymethacrylic acid and polystyrene sulfonate reversibly inhibit dilute β-glucuronidase by sequestering its activator with which they form complexes. Enzyme and inhibitor compete with each other for the activator. The potency of the inhibition depends on the chemical nature of the activator and on its concentration, a mechanism which results in an antagonism between inhibitor and activator. 4. 4. The products of dissociation of β-glucuronidase are irreversibly altered upon contact with rough surfaces, such as scratched glass or quartz sand, inasmuch as the addition of activators no longer restores the original enzyme activity. Thus, handling of diluted β-glucuronidase in ordinary glassware causes an irreversible inactivation. 5. 5. The inactivation can be prevented by the presence of activators during the contact with glass, or it can be boosted by the presence of polymethacrylate or polystyrene sulfonate. Concentrated enzyme solutions are stable in glass, and diluted enzyme solutions are not inactivated in polyethylene containers.

THE ENZYMIC ACTIVITY OF THE DUODENAL CONTENTS FOLLOWING THE INGESTION OF PANCREATIN

The purpose of this article is to demonstrate that a pancreatin containing the three active ferments trypsin, steapsin and amylopsin, properly administered by mouth, on reaching the duodenum will retain a considerable proportion of its original enzymic activity. Long 1 has shown experimentally on dogs with Pawlow pouches that the amylopsin of a pancreatic extract is quickly reduced in activity or destroyed by the hydrochloric acid of the gastric secretion. He also noted that trypsin retained a large percentage of its activity if protected by food proteins from the digestive action of the hydrochloric acid-pepsin combination. From this he concluded that trypsin, thus protected, would unquestionably reach the duodenum and there exert its specific digestive action. There are no available studies as to the fate of lipase administered by mouth. The studies of Long did not include an examination of the duodenal contents for pancreatic extract that had passed on into