The activation of pancreatic extract

Abstract

Many years ago Heidenhain demonstrated that the pancreas does not contain trypsin in an active form, but that it exists in the pancreatic tissue as a proferment or zymogen. Heidenhain was able to convert pancreatic zymogen into active trypsin by treating pancreas with weak acids. This fact was later confirmed by other investigators. Hekma, who used pancreatic juice obtained from a fistula, observed that the trypsinogen of the juice cannot be activated by treatment with acid. In 1899, Pawlow and Schepowalnikow discovered, in the mucosa of the small intestine, a specific substance which converts trypsinogen into active trypsin, and which activates both pancreatic extract and pancreatic juice. Vernon, in a series of papers published in 1901 and 1902 studied the activation of trypsinogen. His observations were largely upon pancreatic extract, although in some instances he used pancreatic juice. His conclusions are as follows: fresh pancreas shows no enzymotic activity; upon standing a few days extracts suddenly develop nearly their maximal tryptic activity; the addition of small quantities of active pancreatic extract increases enormously the rate of conversion of zymogen into active enzyme; fresh pancreas treated for twenty hours with 0.2 per cent. acetic acid develops active trypsin. Using dog's pancreatic juice, Vernon claims that one per cent, active pancreatic extract liberates three times more trypsin than one per cent, succus entericus.