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Copper transfer from Rhus vernicifera laccase.
K A Meadows1, M M Morie-Bebel, D R McMillin
1Department of Chemistry, Purdue University, West Lafayette, IN 47907-3699.
Journal of Inorganic Biochemistry
|March 1, 1991
Summary
Tree laccase, a multi-copper oxidase, shows limited copper transfer to blue copper proteins, indicating inherent heterogeneity. This suggests specific copper types, not all, are available for transfer in physiological processes.
Area of Science:
- Biochemistry
- Bioinorganic Chemistry
- Protein Science
Background:
- Tree laccase is a multi-copper oxidase enzyme.
- Blue copper proteins are important biological electron transfer agents.
- Understanding copper transfer mechanisms is crucial for biological processes.
Purpose of the Study:
- To investigate copper transfer from tree laccase to demetalated blue copper proteins.
- To characterize the heterogeneity of copper in isolated tree laccase.
- To elucidate the roles of different copper types in laccase's donor capabilities.
Main Methods:
- Copper transfer assays using tree laccase and demetalated blue copper proteins under reducing conditions.
- Electron Paramagnetic Resonance (EPR) spectroscopy to analyze copper states.
- Thiol titrations to quantify accessible copper sites.
Main Results:
- Limited (approx. 10%) copper transfer observed, suggesting laccase heterogeneity.
- Laccase resolved into copper-deficient and holoprotein fractions post-transfer.
- EPR and titration data indicate loss of type 2 and some type 3 copper, but not type 1 copper.
Conclusions:
- Isolated tree laccase is heterogeneous in its copper donation.
- Type 2 copper is primarily involved in transfer to blue copper proteins.
- Findings offer insights into physiologically relevant copper transfer mechanisms.