ИСТИНА

Ionic Liquids (ILs), thanks to their tailor-made chemical, physical and biological special properties, are emerging as new solvents for applications in electrochemistry, biocatalysis and drug formulation. The possibility to use enzymes in neat non-conventional media (i.e., ILs, organic solvents) is usually exploited for synthetic applications because of several advantages, such as the possibility to avoid side reactions due to water, to increase the solubility of hydrophobic substrates or to modulate some properties as regio- and enantioselectivity of the biocatalyst. In this perspective the use of ILs as media for synthetic purposes seems to be very promising because of the large number of available ILs. Contrarily to biocatalysis carried out in organic solvents, where enzymes are usually suspended in the reaction system, with an appropriate ILs it is possible to use them in soluble form, which can be a situation helpful to reduce diffusional limitations and to improve enzyme performances. Besides biocatalysis, ILs might be exploited as solvent and/or co-solvents in other protein-based biotechnological applications. ILs can favor the solubilization of protein based polymers from biomass (e.g., fibroin, keratins) [1] or the refolding of proteins, such as intracellular inclusion bodies [2]. However, media that do interact with proteins making them soluble (e.g. some ILs or DMSO or DMF) usually also interfere with intramolecular bonds, causing unfolding and deactivation [3]. In order to shed light on the exploitability to use neat ILs for enzyme dissolution, here we have investigated the solubility of formate dehydrogenase from bacterium Pseudomonas sp. 101 in different ILs and their effects on the stability. The aqueous solution of the enzyme was lyophilized and the dry product re-dissolved with ILs. With [EMIM][DMP], [Et3NMe][MeSO4], [Et3NH3][NO3], [DMPA] [formate] and [Bmim][acetate] the enzyme retained some residual activity, even though only with [Et3NH3][NO3], [DMPA] [formate] and [Bmim][acetate] the enzyme was solubilized. These promising results suggest the use of ionic liquids as alternative solvents for enzyme dissolution in different biotechnological areas. This work was supported by joint grant between Italian National Research Council (Prot. n. 421- 09-03-2015) and Russian Foundation for Basic Research 15-54-78035