ACTION OF SOME EFFECTORS ON HYDROLYSIS OF LONG-CHAIN TRIGLYCERIDES BY PANCREATIC LIPASE

In order to study the action of various effectors on lipolysis of emulsified longchain triglycerides by pancreatic lipase a simple system was used. It was composed of the two reactants, triglyceride and water, with NaCl and a trace of oleate for the stabilization of the emulsions. The initial effect of NaCl is to favor the normally poor ionization of long chain acids at pH 9.0. In the system described above, lipase was very active at the beginning of the reaction. However, early inhibition was observed. This inhibition is caused by the long-chain soaps formed during the reaction. Ca2+ and deoxycholate were not found to appreciably increase the initial rate of lipolysis, but rather to prevent to some extent the inhibitory effect of long-chain soaps. Higher concentrations of deoxycholate and of other bile salts were inhibitory. Lipolysis did not appear to take place in this system unless some NaCl was added. In the presence of increasing NaCl concentrations, the initial rate soon reached a maximum and then decreased. Various mechanisms are discussed for the inhibition of lipolysis by soaps and for the observed effect of Ca2+, bile salts and NaCl. © 1968.