Studies in bile salt solutions. VI. Micellar catalysis of ester hydrolysis by bile-salt-stimulated human milk lipase

Abstract

The reactivity of 4-nitrophenylacetate has been examined in the presence of human milk lipase stimulated by solutions of sodium cholate, deoxycholate, and chenodeoxycholate, and their taurine and glycine conjugates, in 0.01 mole dm −3 bistris propane buffer at pH 6.50, T = 310.5°K. The reactivity of phenylsalicylate (salol) has also been examined in the presence of sodium cholate. The rate constant-bile salt concentration profiles have been analyzed according to the pseudophase micellar model and the values of the binding constant, K HML, between the enzyme and the various bile salts, the kinetic values of the critical micelle concentrations, CMC, and the values of the micelle-catalyzed rate constants, k M , have been identified.