Computational Design of a Highly Stable Dicopper Catechol Oxidase
Vanessa H Eng1, Sarah M Narehood1, Yiying Li1
1Department of Chemistry, University of California, San Diego, La Jolla, California 92093, United States.
Journal of the American Chemical Society
|February 18, 2026
Summary
Researchers designed a small, stable di-copper protein (Cu-HC4) that mimics natural copper oxidases, showing efficient diphenol oxidation and melanin production. This engineered protein offers insights into enzyme structure-function relationships.
Area of Science:
- Biochemistry
- Protein Engineering
- Enzyme Catalysis
Background:
- Type 3 (T3) copper proteins are vital for oxygen activation across life.
- Natural T3 Cu proteins exhibit diverse functions like oxygen transport (hemocyanin) and catalysis (tyrosinase, catechol oxidase).
- Understanding the structural basis for catalytic activity in T3 Cu proteins remains an active research area.
Purpose of the Study:
- To design and characterize a novel di-copper protein (Cu-HC4) inspired by T3 Cu protein active sites.
- To investigate the structural determinants of catalytic oxidase activity in engineered copper proteins.
- To explore the potential of Cu-HC4 in mimicking natural enzyme functions, such as melanin biosynthesis.
Main Methods:
- Protein design and engineering of Cu-HC4 with reduced size and sequence identity to natural T3 Cu proteins.
- Biochemical assays to assess diphenol oxidation activity and thermostability.
- Mechanistic studies to elucidate the catalytic pathway and oxygen dependence.
- Cryo-electron microscopy (Cryo-EM) to determine the structure of tetrameric Cu-HC4.
Main Results:
- Cu-HC4, significantly smaller than mushroom tyrosinase, demonstrates high thermostability and effective diphenol oxidation activity.
- The engineered protein initiates melanin polymer formation, similar to natural tyrosinases.
- Mechanistic studies reveal cooperative utilization of both copper centers and oxygen requirement for catalysis.
- Cryo-EM identified subtle structural differences in active site residues compared to natural T3 Cu enzymes, potentially explaining reactivity variations.
Conclusions:
- The designed di-copper protein Cu-HC4 exhibits robust oxidase activity and mimics key functions of natural T3 Cu enzymes.
- Structural insights from Cu-HC4 provide a deeper understanding of structure-function relationships in copper-dependent oxidases.
- This work opens avenues for developing novel bio-inspired catalysts with tailored enzymatic properties.
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