Abstract
The activity and stability of commercial laccase (DeniLite base) in three different water soluble ionic liquids (ILs) (1‐ethyl‐3‐methylimidazolium 2‐(2‐methoxyethoxy) ethylsulfate, [emim][MDEGSO~4~], 1‐ethyl‐3‐methylimidazolium ethylsulfate, [emim][EtSO~4~], and 1‐ethyl‐3‐methylimidazolium methanesulfonate, [emim][MeSO~3~]) have been studied and compared to that in two organic solvents (acetonitrile and dimethyl sulfoxide). Initial enzyme activities were similar among the ILs if the same conditions were used. A high reduction on initial enzyme activity was found with acidic pH (5.0). The effect of pH and solvent concentration on enzyme stability were investigated in more detail for 1 week. The enzyme maintained a high stability at pH 9.0 for all ILs tested. [emim][MDEGSO~4~] was the most promising IL for laccase with an activity loss of about 10% after 7 days of incubation. The kinetic studies in the presence of ABTS as substrate allowed to calculate the Michaelis– Menten parameters. Good agreement was found between experimental data and calculated values using the Michaelis–Menten mechanism, with a total average relative deviation of 2.1%. Biotechnol. Biotechnol. Bioeng. 2008;101: 201–207. © 2008 Wiley Periodicals, Inc.