Related Experiment Video
Updated: Sep 25, 2026

Quantification of Hypopigmentation Activity In Vitro
Published on: March 6, 2019
Inhibitory effects of some flavonoids on the activity of mushroom tyrosinase
Li-Ping Xie1, Qing-Xi Chen, Huang Huang
1Department of Biological Science and Biotechnology, Center for Ocean Science and Engineering, Protein Science Laboratory of Ministry of Education, Tsinghua University, Beijing, 100084, P. R. China.
Abstract:
Mushroom tyrosinase (EC 1.14.18.1) is a copper containing oxidase that catalyzes both the hydroxylation of tyrosine into o-diphenols and the oxidation of o-diphenols into o-quinones, and then forms brown or black pigments. In the present study, the effects of some flavonoids on the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) have been studied. The results show that flavonoids can lead to reversible inhibition of the enzyme. A kinetic analysis showed that the flavonols are competitive inhibitors, whereas luteolin is an uncompetitive inhibitor. The rank order of inhibition was: quercetin > galangin > morin; fisetin > 3,7,4;-trihydroxyflavone; luteolin > apigenin > chrysin.
Related Concept Videos
Enzyme Inhibition
Feedback Inhibition
Indirect-Acting Cholinergic Agonists: Mechanism of Action
Reversible inhibitors like edrophonium bind to a specific part of the enzyme called the anionic catalytic site. They form noncovalent bonds, which means they are not strongly attached to the enzyme. This creates a temporary and less stable enzyme–inhibitor complex, leading to...
Epistasis