Supercritical Fluids as Solventsfor Enzymatic Reactions

Maja Habulin, Mateja Primožič and Željko Knez
University of Maribor, Faculty of Chemistry and Chemical Engineering,Smetanova 17, 2000 Maribor, Slovenia, fax: +386 2 25 27 774

Enzymes may act in different solvent systems. Water as the solvent in vivo may be replaced partially or mostly with other solvents, such as micro-emulsions, organic solvents, reversed micelles, ionic liquids and supercritical fluids (SCFs).Several types of enzymatic reactions were performed in SCFs. Influence of SCFs on enzyme stability and activity is presented on different examples; on different reaction systems (hydrolysis, transesterification …) and on the use of non-immobilized (Subtilisin carlsberg, Aspergillus niger …) as well as immobilized enzymes. Several types of high-pressure enzymatic reactors (batch-, stirred-tank-, extractive semibatch-, recirculating batch-, semicontinuous flow-, continuous packed-bed-, and continuous-membrane reactors) have been used for the performance of enzymatic reactions. In the studies on stability of biocatalysts in a high-pressure batch-stirred tank reactor changes in biocatalysts activity due to pressurization/depressurization steps were observed. Interesting alternative to overcome this inconvenience is the use of the high-pressure continuous membrane reactors, where just single compression and expansion step is necessary.

Keywords: Enzymatic reactions, supercritical carbon dioxide, high-pressure, enzyme stability, high-pressure reactors …S