Inhibition of Catalase Activity in Wines

¹ Department of Viticulture and Enology, University of California, Davis 95616.

Catalase (fungal source) was found to be essentially completely inhibited by wine concentrations of ethanol. The inhibition is noncompetitive and apparently involves the binding of the ethanol with the enzyme in the compound I form, thereby inhibiting the catalatic reaction. The peroxidatic reaction then is either extremely slow, or does not proceed to form acetaldehyde, but removes the enzyme from further catalatic reactions. The K_m of the reaction (H₂O₂ H₂O + O₂) is 0.02 M and V_max was 2.2 x 10³ µ moles/min. Malic acid, grape seed tannin, catechol, chlorogenic acid and gallic acid did not affect catalase activity. The ethanol concentration in wine accounts for essentially all the inhibition found.