Ionic liquids as alternative co‐solvents for laccase: Study of enzyme activity and stability

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][[MDEGSO4], 1-ethyl-3-methylimidazolium ethylsulfate, [emim][EtSO4], and 1-ethyl-3-methylimidazolium methanesulfonate, [emim][MeSO3]) 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][MDEGSO4] 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%.

Effect of Glycosylation of β-Glucuronidase on its Catalytic Properties in Ionic Liquids

“…ILs like 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF 6 ) and 1-butyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF 4 ) are known to be good alternatives to organic solvents in bioconversion 22 . The use of ILs in enzymatic reactions leads to remarkable improvements in thermostability, stereoselectivity, regioselectivity, and inhibition of side reactions [23][24][25][26][27] . ILs are also known as rather toxic solvents, since they can influence the stability and activity of enzyme through the anions' nucleophilic properties and hydrogen bonding [28][29][30] .The interaction formed by hydrogen bonds between anion and enzyme is very strong, which may cause a conformational change in the enzyme, thus affecting the enzyme activity.…”

Ionic Liquids: Alternative Reactive Media for Oxidative Enzymes

“…These first results of laccase kinetics suggested that the optimization of reaction conditions in ionic liquids may be necessary to obtain higher catalytic activities. Another work can be referred with laccase (Tavares et al, 2008) Enzymatic inhibition is another point that should be considered in kinetics. An inhibitor is any substance that reduces the reaction rate.…”

Developing energy efficient lignin biomass processing – towards understanding mediator behaviour in ionic liquids

“…In addition, there are difficulties associated with the use of LMS in conventional solvents. [28][29][30][31] In contrast to LMS, an electrolytic mediator system (EMS) (Figure 1b) could provide a promising and effective alternative for lignin depolymerisation. Instead of using a laccase to oxidise the mediator, the mediator can be oxidised electrochemically instead.…”