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Chemical and enzymic oxidation by tyrosinase of 3,4-dihydroxymandelate.

The Biochemical journal (1988-12-01)
J Cabanes, A Sanchez-Ferrer, R Bru, F García-Carmona
ABSTRACT

Tyrosinase usually catalyses the conversion of monophenols into o-diphenols and the oxidation of diphenols to the corresponding o-quinones. Sugumaran [(1986) Biochemistry 25, 4489-4492] has previously proposed an unusual oxidative decarboxylation of 3,4-dihydroxymandelate catalysed by tyrosinase. Our determination of the intermediates involved in the reaction demonstrated that 3,4-dihydroxybenzaldehyde is not the first intermediate appearing in the medium during the enzymic reaction. Re-examination of this new activity of tyrosinase has demonstrated that the product of the enzyme action is the o-quinone, which, owing to its instability, evolves to the final product, 3,4-dihydroxybenzaldehyde, by a chemical reaction of oxidative decarboxylation.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
DL-3,4-Dihydroxymandelic acid, 95%