TECHNOLOGY / APPLICATION / BIOCATALYSIS

BIOCATALYSIS

Biocatalytic reactions and processes in ionic liquids are a relatively new area of research [1]. They are thought to overcome the challenges associated with these processes such as substrate solubility, selectivity and stability of the enzymes.

Generally there are three ways to use ionic liquids in a biocatalytic process:

• as a pure solvent (lipase, reverse hydrolysis, transestrification)
• as a co-solvent in aqueous systems (galactosidase, oxidoreductases)
• in a biphasic system (whole cells)

In the first case the appropriate control of the water content in order to maintain the enzyme's activity is of crucial importance. The hydrophobic ionic liquid [BMIM][PF₆] for example has been used for in situ extraction in bioprocesses [2]. Water-miscible ionic liquids such as [BMIM][BF₄] or ECOENG^TM 1111P   can be used in the second case.

When using ionic liquids with biocatalysts some important aspects have to be taken into consideration. First, impurities in the ionic liquid can result in pH-shifts leading to inactivation of the enzyme. These impurities may also act as reversible or irreversible enzyme inhibitors. Therefore chloride contents or residual starting materials of the ionic liquid should be known prior to their use. Secondly, water present in the reaction system may lead to hydrolysis of some ionic liquids. Thirdly, some enzymes require metal ions for their activity, if these ions are complexated by the ionic liquid inactivation of the enzyme may occur.

As for the enzyme-friendliness of a given solvent, the log P concept which is based on the distribution coefficient between water and octanol has been used as a guideline [3]. So far ionic liquids have not been treated according to this concept, however the polarities of ionic liquids have been investigated by different groups [4].

Solvent Innovation offers a biotechnology kit with specially selected ionic liquids.

For detailed information about which biocatalytic reactions have been performed in ionic liquids have been used please contact markus.wagner@solvent-innovation.com

[1] van Rantwijk, F.; Madeira Lau, R.; Sheldon, R. A. Trends in Biotechnology 2003 , 21 , 131. "Biocatalytic transformations in ionic liquids" ; U. Kragl et al. Ionic Liquids  in Synthesis, 2003, Wiley-VCH, Weinheim

[2] A. G. Fadeev, M. M. Meagher, Chem. Commun. , 2001 , 295

[3] C. Laane et al. Biocatalysis in organic media , Elsevier, Amsterdam, 1987

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