抄録
Pancreatic lipase activity toward vinyl laurate (VL) solubilized in sodium deoxycholate (NaDC) micelles was investigated kinetically. The inhibition by substrate-free NaDC micelles, M, was observed, and a Lineweaver-Burk plot and a plot of the reciprocal of initial rate vs. [M] indicated that the inhibition may be fully competitive or fully mixed inhibition, depending on the value adopted for the aggregation number of NaDC micelles. However, further consideration of the interaction of various species in the system led us to favor a fully competitive inhibition mechanism. The Michaelis constant, Km, and the inhibition constant, K4, which is the dissociation constant of lipase-NaDC micelle complex, were estimated. It was shown that Km indicates the lower limit of the dissociation constant of lipase-NaDC micelle solubilizing VL, K1. The results are discussed in relation to the results of other studies on the inhibition of the enzyme by bile salts in emulsion systems.
