Showing papers by "Eamonn F. Healy published in 1988"
TL;DR: The mixedmicelle system is ideally suited for inhibition studies with phospholipase A2 since both the inhibitor and substrate can compete for the binding to the active site of the enzyme in the surface of the mixed micelle and is free from the complexities that arise from lipid-lipid interactions.
Abstract: the present work we show that the mixed micelle system is ideally suited for inhibition studies with phospholipase A2 since both the inhibitor and substrate can compete for the binding to the active site of the enzyme in the surface of the mixed micelle and is free from the complexities that arise from lipid-lipid interactions. Although the mixed-micelle system is perhaps a poor model of a biological membrane, it provides a reliable method for ranking inhibitors according to their relative free energies of interaction with the enzyme. Mixed micelles for inhibition studies were prepared by soni- cating fixed amounts of Triton X-100 (40 mM) and substrate (dipalmitoyl phosphatidylcholine, 5 mM) with variable amounts of inhibitor in water-containing CaC12 (10 mM).I2 Enzyme was added, and the reaction velocity was determined in a pH-stat at pH 8.0 and 40 T9 The initial enzymatic velocity as a function of the concentration of inhibitor
23 citations
TL;DR: In this paper, the authors show that the mixed micelle system is ideally suited for inhibition studies with A2 since both the inhibitor and substrate can compete for the binding to the active site of the enzyme in the surface of the mixed-micelle and is free from the complexities that arise from lipid-lipid interactions.
Abstract: the present work we show that the mixed micelle system is ideally suited for inhibition studies with phospholipase A2 since both the inhibitor and substrate can compete for the binding to the active site of the enzyme in the surface of the mixed micelle and is free from the complexities that arise from lipid-lipid interactions. Although the mixed-micelle system is perhaps a poor model of a biological membrane, it provides a reliable method for ranking inhibitors according to their relative free energies of interaction with the enzyme. Mixed micelles for inhibition studies were prepared by soni- cating fixed amounts of Triton X-100 (40 mM) and substrate (dipalmitoyl phosphatidylcholine, 5 mM) with variable amounts of inhibitor in water-containing CaC12 (10 mM).I2 Enzyme was added, and the reaction velocity was determined in a pH-stat at pH 8.0 and 40 T9 The initial enzymatic velocity as a function of the concentration of inhibitor
TL;DR: The magnitudes of secondary deuterium isotope effects (SDIE) are generally in the range of 0.9 − 1.25 as discussed by the authors, and are often satisfactorily rationalized by the zero point energy (ZPE) change on going from reactant to transition state due to C-H rehybridization.
Abstract: The magnitudes of secondary deuterium isotope effects (SDIE) are generally in the range of 0.9 < k/sub H//k/sub D/ < 1.25, and are often satisfactorily rationalized by the zero-point energy (ZPE) change on going from reactant to transition state due to C-H rehybridization. They now report a far larger SDIE for the title reaction. Its rationalization on the basis of transition state theory suggests that it more closely resembles a primary isotope effect.