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Endothelin-converting enzyme: the binding of metal ions
1Department of Chemistry and Biochemistry, University of Colorado, Boulder.
International Journal of Peptide and Protein Research
|July 1, 1993
Summary
Endothelin-converting enzyme (ECE) activity was studied using metal ion replacement. Results indicate that only zinc ions can serve as the native metal cofactor for ECE, maintaining its full enzymatic function.
Area of Science:
- Biochemistry
- Enzymology
- Metalloprotein
Background:
- Endothelin-converting enzyme (ECE) is a key metalloproteinase involved in regulating blood pressure.
- Identifying the native metal cofactor of ECE is crucial for understanding its catalytic mechanism and for drug development.
Purpose of the Study:
- To determine the specific metal ion essential for the catalytic activity of endothelin-converting enzyme (ECE).
- To investigate the impact of various divalent metal ions on ECE activity and compare it to the native enzyme.
Main Methods:
- Enzyme inhibition using ethylenediaminetetraacetic acid (EDTA) to chelate the native metal ion.
- Restoration of ECE activity by adding specific divalent metal salts at concentrations lower than EDTA.
- Quantification of relative enzyme activity for different metal ion substitutions (Fe, Mn, Ni, Cu, Zn, Co).
Main Results:
- ECE activity was significantly reduced with copper (17%) and cobalt (122%) ions showed altered activity.
- Zinc (98%), ferrous (76%), manganous (76%), and nickelous (77%) ions partially or fully restored enzyme activity.
- Only zinc ions fully reconstituted the native enzyme's activity, exhibiting identical Km and turnover number.
Conclusions:
- Zinc is the essential native metal ion cofactor for endothelin-converting enzyme (ECE).
- The zinc-substituted ECE enzyme mirrors the kinetic properties of the native enzyme, confirming its role.