Kinetic and Stability Study of the Peroxidase Inhibition in Ionic Liquids
Résumé
The activity and stability of peroxidase in aqueous solutions of two ionic liquids (ILs) have been studied. The ILs selected were 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate, [emim][MDEGSO 4 ], and 1-ethyl-3-methylimidazolium ethylsulfate, [emim][EtSO 4 ]. Experiments were performed at room temperature using concentrations of ILs between 5 and 50% (v/v) and pH values in the range from 5 to 9. The initial activity of the enzyme in these ILs at optimized conditions (pH 7 and 5-10% IL) was similar or higher than that achieved with buffer solution. Kinetic studies showed that maximum reaction velocity (V max) decreased with increasing concentration of IL. The effect of [emim][EtSO 4 ] concentration on the decrease of V max was higher than that of [emim][MDEGSO 4 ]. It was found that [emim][EtSO 4 ] was a more potent inhibitor on peroxidase activity. The peroxidase studied was active in the ILs investigated, and the enzyme exhibited a higher stability in ILs at the optimized conditions. Kinetic studies showed that inhibition was a noncompetitive type in both ILs.