INTRACELLULAR DISTRIBUTION OF LIPASE IN COMPARISON TO TRYPSINOGEN AMYLASE AND IMMEDIATELY MEASUREABLE TRYPSIN INHIBITOR(S) IN RAT PANCREAS

The intracellular distribution of lipase (glycerol ester hydrolase EC 3.1.1.3.), trypsinogen (EC 3.4.4.4.), amylase (EC 3.2.1.1.) and immediately measurable trypsin inhibitor(s) has been studied using isopycnic gradient centrifugation of rat pancreatic homogenates. A modified method for the measurement of trypsinogen is presented and a micromethod for the estimation of trypsin inhibitory activity is described. By comparison with lipase smaller proportions of the total trypsinogen and amylase activities were recovered from the zymogen fractions. The total immediately measurable trypsin inhibitory activity was mainly localised in the cytomembrane fractions, while virtually no activity was found in the zymogen granules. The specific activity (activity per mg protein) for both amylase and trypsinogen was high in the zymogen and in the cell sap fractions. For lipase and immediately measurable trypsin inhibitory activity, however, the specific activity was high only in the zymogen granules and cytomembranes, respectively. © 1969 Scandinavian Physiological Society