Inhibition of Agaricus tyrosinase by 1, 5-anhydro-D-fructose and its application to anti-browning of food materials

Abstract

1, 5-Anhydro-D-fructose (1, 5-AF), which is produced from starch by the action of alpha-1, 4-glucan lyase, competitively inhibited Agaricus tyrosinase (L-tyrosine, L-dopa: oxygen oxidoreductase, EC 1.14.18.1) with a Ki value of ~20 mM. In silico modelling of the catalytic subunit of the enzyme docked with a 1, 5-AF molecule showed that only the keto form of the 1, 5-AF molecule could bind to the bottom of the active site of tyrosinase. The binding mode seemed to be very similar to that of tropolone, a strong, competitive inhibitor. 1, 5-AF also inhibited an enzyme partially purified from wheat flour and retarded the browning of commercial avocado paste. Thus, its colour protection activity, in conjunction with its bacteriostatic effect, appears applicable to food processing.