earticle

영어

To explore the effects of the ionic liquids on enzymatic catalyses, the horseradish peroxidase catalyzed oxidation of 2-methoxyphenol with H2O2 was studied in the aqueous mixtures of the three ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), N-butyl-3- methypyridinium tetrafluoroborate ([BMPy][BF4]), and 1-butyl-3- methylimidazolium methylsulfate ([BMIM][MeSO4]). [BMIM][BF4] and [BMPy][BF4] share an anion (BF4 -) while [BMIM][BF4] and [BMIM][MeSO4] have a cation (BMIM+) in common. On the addition of [BMIM][BF4] or [BMPy][BF4], Km increased while kcat decreased. In the aqueous mixtures of [BMIM][ MeSO4], however, both Km and kcat decreased. Equilibrium partitioning of the substrate with n-octanol as a standard solvent revealed that the three ionic liquids stabilize the free substrate resulting in the diminished binding affinity of the substrate onto the enzyme. Based on these kinetics and thermodynamics investigations, anionic parts of the ionic liquids are presumed to exert a major role to determine how the enzymatic catalysis is affected by the ionic liquids; BF4 - inhibits the enzyme non-competitively, but MeSO4 - uncompetitively.