ENZYMATIC CATALYSIS IN ORGANIC MEDIA

The extension of enzymatic catalysis, classically carried out in aqueo us media, to organic media can be first ascribed to the possibility of using substrates that are poorly soluble or insoluble in water. In bi phasic media consisting of an aqueous phase containing the enzyme in s olution and of a non water-miscible organic solvent, the enzyme is kep t in a suitable aqueous environment. A variant biphasic system consist s in creating reverse micelles by the addition of a surfactant in orde r to increase the interfacial area and thus to improve the transfers b etween the aqueous phase where the enzyme is located and the organic p hase. In these two cases, the partition coefficient of the different r eactants plays a crucial role by governing the rates and yields of rea ction. Microaqueous media constitute a new system for biocatalysis in organic media. In this case, a solid enzyme is incorporated into an or ganic solvent, preferably a hydrophobic one, wherein it exhibits new p roperties, especially a higher stability and a modified selectivity. T he enzymes the most studied in this type of medium are hydrolytic ones , such as lipases or proteases which can then catalyze synthesis react ions. Yet, other classes of enzymes have also been used in this way. A s oil products are typical hydrophobic compounds, it was of interest i n view of possible applications in the petroleum and petrochemical ind ustries to report the present knowledge about the functioning of enzym es in organic media. The present and potential applications of the mos t studied enzymatic systems will be reviewed in order to point out the major points of interest of biocatalysis in organic media either for organic synthesis or for less investigated fields, such as, for instan ce, biodegradation of pollutants by whole cells.