Improving Enzymes by Using Organic Solvents
Enzymes naturally work in aqueous medium, which becomes a limitation when used in industrial bioconversions for the following reasons: (i) Most industrial bioconversions are insoluble in water; (ii) water often gives rise to unwanted side reactions and degrades common organic reagents; (iii) thermodynamic equilibria of many processes are unfavourable in water; (iv) product recovery is sometimes difficult from aqueous medium. Although most of these problems can be overcome by switching from water to organic solvents as the reaction media, but most enzymes are denatured and lose their catalytic activity in organic solvents, particularly when aqueous-organic mixtures are used. However, it has been shown that when dry (anhydrous)     organic solvents are used, denaturation may not take place.

 Reverse reaction (synthesis of esters) also becomes thermody-namically favourable. (ii) Although catalytic acitivity is lower in organic solvents, but remedies for this are emerging. For instance, alterations in pH aq. Solutions affects catalytic activity, but no such alterations in pH occur in organic solvents, where the enzymes activity can be maximized by adding buffer pairs (acids with their conjugate bases).
The structural flexibility of enzyme, which is key to optimal catalysis, also depends on water, but it has been shown that addition of small quantities of water, glycerol or ethylene glycol which like water are capable of forming hydrogen bonds) to anhydrous enzyme leads to loosening up of enzyme.