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Inhibitory Effects of Cupferron on the Monophenolase and Diphenolase Activity of Mushroom Tyrosinase

Inhibitory Effects of Cupferron on the Monophenolase and Diphenolase Activity of Mushroom Tyrosinase

Li Ping Xie, Qing Xi Chen, Huang Huang, Xiao Dan Liu, Hong Tao Chen, Rong Qing Zhang

Int J Biochem Cell Biol. 2003 Dec;35(12):1658-66.

PMID: 12962705

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. In the present study, the kinetic assay was performed in air-saturated solutions and the kinetic behavior of this enzyme in the oxidation of L-tyrosine and L-DOPA has been studied. The effects of cupferron on the monophenolase and diphenolase activity of mushroom tyrosinase have been studied. The results show that cupferron can inhibit both monophenolase and diphenolase activity of mushroom tyrosinase. The lag phase of tyrosine oxidation catalyzed by the enzyme was obviously lengthened and the steady-state activity of the enzyme decreased sharply. Cupferron can lead to reversible inhibition of the enzyme, possibly by chelating copper at the active site of the enzyme. The IC(50) value was estimated as 0.52 microM for monophenolase and 0.84 microM for diphenolase. A kinetic analysis shows that the cupferron is a competitive inhibitor for both monophenolase and diphenolase. The apparent inhibition constant for cupferron binding with free enzyme has been determined to be 0.20 microM for monophenolase and 0.48 microM for diphenolase.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP135206	Cupferron		135-20-6	Price

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