Laccase denaturation

Mozhaev W, Khmelnitsky Y, Sergeeva MV et al. (1989) Catalytic activity and denaturation of enzymes in water/organic cosolvent mixtures. Alpha-chymotrypsin and laccase in mixed wa-ter/alcohol, water/glycol and water/formamide solvents. Eur J Biochem 184 597-602 Nagasawa T, Yamada H (1990) Large-scale bioconversion of nitriles into useful amides and acids. 

The results of investigations of enzymatic activity in the immobilized state. When laccase, peroxidase, and other enzymes are adsorbed on dispersive electroconductive carriers, their enzymatic activity perceptibly declines, thus indicating a denaturing of part of the macromolecules. In this case, however, there is a sufficient quantity of denatured enzyme molecules strongly bonded with the carrier, which display a specific biocatalytic activity in model reactions of the substrates. It is these molecules of the enzyme, as will be seen further, that are responsible also for the electrocatalytic activity of the system. 

A sufficient and controlled addition of oxygen as soon as cellular structures are degraded provokes the denaturation of tyrosinase during the oxidation reactions that it catalyzes. The disappearance of the enzyme and the depletion of oxidizable phenolic substrates thus make the must stable with respect to oxidation. The condensation products responsible for browning should be eliminated before fermentation. Dne to its possible impact on aromatic elements, this technique seems better adapted to certain cultivars. It is not applicable to botrytized grapes, due to the resistance of laccase. 

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