Study of the Alkyl Chain Length on Laccase Stability and Enzymatic Kinetic with Imidazolium Ionic Liquids

The activity and stability of laccase and their kinetic mechanisms in water soluble ionic liquids (ILs): 1-butyl-3-methyl imidazolium chloride [C(4)mim][Cl], 1-octyl-3-methyl imidazolium chloride [C(8)mim][Cl], and 1-decyl-3-methyl imidazolium chloride [C(10)mim][Cl] were investigated. The results show that an IL concentration up to 10% is satisfactory for initial laccase activity at pH 9.0. The laccase stability was well maintained in [C(4)mim][Cl] IL when compared to the control. The inactivation of laccase increases with the length of the alkyl chain in the IL: [C(10)mim][Cl] > [C(8)mim][Cl] > [C(4)mim][Cl]. The kinetic studies in the presence of ABTS as substrate allowed calculating the Michaelis-Menten parameters. Among the ILs, [C(4)mim][Cl] was the suitable choice attending to laccase activity and stability. Alkyl chains in the ions of ILs have a deactivating effect on laccase, which increases strongly with the length of the alkyl chain.