A statistical analysis of the main effects and interactions of pH, taurocholate and calcium on pancreatic lipase activity

Abstract

A factorial experiment was used to determine the nature of the effects of pH, [taurocholate] and [Ca 2+] on the rate of hydrolysis of long-chain triglycerides by pig pancreatic lipase. A stable emulsion of triolein was used as substrate. Statistical analysis showed that there were significant interactions between the three factors. Under the particular conditions of substrate and emulsion used, the following effects were found: In the presence of taurocholate and calcium ions the rate of hydrolysis increased in a non-linear fashion from pH 7.5 to 9.5. The overall effect of [taurocholate] in the presence of calcium ions showed an optimum at about 6.9 mM (0.37%, w/v). [Ca 2+] showed a similar optimum at about 40 mM. Although there was interaction between pH and [taurocholate], the plots of reaction rate vs. pH had the same general shape and position on the pH axis for all values of [taurocholate]. There was pronounced interaction between pH and [Ca 2+]; optimum [Ca 2+] was highly dependent on pH, and the reaction rate at higher pH values was highly dependent on [Ca 2+]. The interaction between [Ca 2+] and [taurocholate] involved an exponential function of both.