Abstract
In order to clear the mechanism of activation by bile salts, their effect on Mucor lipase and substrates was studied. Optimum pH of the lipase was not influenced by the salts. Heat stability of the lipase was slightly deteriorated by their addition. Michaelis constant (Km) and maximum velocity (Vmax) for olive oil in the presence of 5×10-3M of sodium taurocholate (VII) were 275 (mg) and 1.68 (mg/min), respectively, against 403 and 1.22 in their absence. Activation of the enzyme and the accelerating effect on the substrates by bile salts were not recognized in any concentration tested, though the physical properties, viscosity and surface tension, did change. The number of enzyme molecules adsorbed at oil-water interface increased by the addition of bile salts. A good proportional relation was found between the rate of increased relative activity and quantities of the enzyme adsorbed at the interface, and the quantity increased in proportion to the increasing concentration of bile salts. Analogous results were obtained with pancreatic lipase, but adsorption of Candida lipase slightly inhibited by the salts decreased by the salts. Diffusion of oleic acid from the interface was markedly increased by the addition of bile salts.
