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Updated: Dec 22, 2025
12:08
Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
15.5K
Copper-Oxygen Dynamics in the Tyrosinase Mechanism
Nobutaka Fujieda1, Kyohei Umakoshi2, Yuta Ochi1
1Department of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka, 599-8531, Japan.
Angewandte Chemie (International Ed. in English)
|May 2, 2020
Summary
Tyrosinase, a copper enzyme, uses substrate binding to move copper ions and rearrange a peroxide ligand. This mechanism facilitates the hydroxylation of phenols to catechols.
Area of Science:
- Biochemistry
- Enzymology
- Structural Biology
Background:
- Tyrosinase is a dinuclear copper enzyme catalyzing the oxidation of phenols.
- The precise mechanism of the tyrosinase phenolase reaction remains incompletely understood.
- Activation of O2 by tyrosinase yields a peroxido dicopper(II) intermediate.
Purpose of the Study:
- To elucidate the mechanism of the tyrosinase-catalyzed phenolase reaction.
- To determine the structural basis for O2 activation and substrate hydroxylation.
- To investigate the role of copper ion movement and peroxide rearrangement.
Main Methods:
- X-ray crystallography at near atomic resolution
- Spectroscopic analyses
- Crystallization of active tyrosinase with l-tyrosine and O2
Main Results:
- Observed near atomic resolution crystal structures of tyrosinase with l-tyrosine.
- Identified substrate-induced copper ion migration (CuA1 → CuA2 and CuB1 → CuB2).
- Demonstrated peroxide ligand rotation and O-O bond weakening, facilitating substrate access.
Conclusions:
- Substrate binding induces copper migration and peroxide rearrangement in tyrosinase.
- This coordinated movement provides an oxygen atom for phenol hydroxylation.
- The findings clarify a key step in the tyrosinase catalytic cycle.
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