Studies on the Effects of Surfactants on Lipase Activity

Abstract

In a series of studies on the application of lipases to detergency, the influence of pH and surfactants on the activities of various lipases was examined by assaying residual lipase activity. Five microbial lipases of Candida cylindracea (Can), Mucor sp. (Mu), Rhizopus chinensis (Rhi), Chromobacterium viscosum (Chr), and Pseudomonas (Pse), and an animal lipase of porcine pancrea (Pan) were used. Two methods A) and B), the prior contact of surfactant with substrate or with lipase, respectively, were used.The following results were obtained : 1) The effects of change in ionic groups on lipase activity were briefly examined by varing the pH of the system. These effects were small for Rhi and Chr but large for Can, Mu, Pse, and Pan.2) In method A, all lipase activity was reduced almost linealy with rise in surfactant concentration. Measurements of the kinetic parameters of lipase hydrolyses indicated the inhibition to be quite likely due to change in the surface properties of substrate as a result of surfactant adsorption.3) In method B, the nonionic surfactant activated each lipase, and the activity was maximum at the characteristic concentration.4) The effects of anionic surfactants in method B varied according to the lipase. Can, Mu, Pse, and Pan were strongly inhibited, while the activity of Rhi and Chr increased once and remained in a wide range of concentration. Maximum Can, Rhi, Chr, and Pse activity in the presence of anionic surfactants may possibly be due to the formation of a new and more active surface lipasesurfactant complex.5) The effects of surfactants at pH 10 were similar to those at pH 7.6) Classification of lipases on the basis of inhibition mode by anionic surfactants was consisted with that by pH effect.7) The inhibition of lipase activity by anionic surfactants could be avoided by mixing nonionic surfactants.