Deep Eutectic Solvents as Media for Peroxidation Reactions Catalyzed by Heme-Dependent Biocatalysts

In the present study, the effect of various choline chloride (ChCl) and ethylammonium chloride (EAC) based deep eutectic solvents (DES), formed with three biodegradable hydrogen bond donors (urea, glycerol, and ethylene glycol), on the catalytic behavior and structure of heme-dependent biocatalysts, such as cytochrome c and horse radish peroxidase, was investigated. The peroxidase activity of biocatalysts strongly depends on the nature of the ammonium salt and hydrogen bond donor used for the formation of DES, as well as on DES concentration in the reaction media. UV vis and circular dichroism spectroscopic studies indicate that the effect of DES on the biocatalytic behavior of cyt c is correlated with heme microenvironment perturbations. Moreover, EAC- based DES stabilize cyt c, enhance its activity for the biodegradation of an industrial dye and, are successfully reused up to four times, indicating that these environmentally friendly solvents could he promising media for biocatalytic processes of industrial interest.