AREAS RELATED TO ENZYME CATALYSIS - New Trends in Enzyme Catalysis and Biomimetic Chemical Reactions - page 166

5.2. Enzymes in organic solvents

In spite of a long-time paradigm that enzymes can be active only in their natural aqueous
media and other solvents cause deactivation and denaturation of proteins, at present a
growing number of investigations are devoted to enzymatic reactions in organic solvents
(Klibanov, 2001; Ke et al., 1996; Koskinen and Klibanov, 1996; and references therein).
Such enzymes as subtilisin ribonuclease, pancreatuc lipase, and horse
radish peroxidase have been found to be markedly active in organic solvents (alcohols,
amines, tiols,anhydrous alkanes, acetonitril, dichloromethane, methyl acetate, etc.).
While enzymes, as a rule, essentially lose their normal activity and specificity, they
possess new useful features: 1) utilization of substrates non-soluble in water; 2) their
ability to change substrate and inhibitor selectivity and specificity; 3) they alternate of
reactions thermodynamics and kinetics reactions so that desirable products are favoured;
4) improvements of enzyme stability; and 5) the possibility to fix enzymes and reaction
intermediates at states of certain pH and ionic strength in both solution and crystal form
('molecular memory effects').
The transfer of enzymes from water to organic solvents is accompanied by a decrease
in their conformational flexibility, desolvation of substrate and catalytic groups,
distortion of active centers, change in acidity and basicity, nuleophilicity and
electrophilicity of functional groups, drastic change in distribution of electrostatic
potential over protein globules including the area of enzyme active sites. For example,