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Acylphosphate formation by the Menkes copper ATPase
1Department of Clinical Pharmacology, University of Berne, Switzerland. solioz@ikp.unibe.ch
FEBS Letters
|July 21, 1997
Summary
The Menkes ATPase enzyme, crucial for copper metabolism, forms an acylphosphate intermediate. This finding provides a direct functional test for this P-type ATPase, important in inherited copper disorders.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- The Menkes ATPase, encoded by the MNK gene, is implicated in inherited human copper metabolism disorders.
- Understanding the enzymatic activity of the Menkes ATPase is critical for elucidating these conditions.
Purpose of the Study:
- To investigate the enzymatic activity of the murine Menkes ATPase homologue.
- To characterize the formation of an acylphosphate intermediate by the Menkes ATPase.
- To establish a functional assay for the Menkes ATPase.
Main Methods:
- Enzyme assays were performed on membranes from normal and copper-resistant Chinese hamster ovary cells.
- Acylphosphate formation was measured under varying conditions.
- Kinetics of phosphorylation, metal dependence, and inhibitor sensitivity were analyzed.
Main Results:
- The murine Menkes ATPase homologue formed an acylphosphate intermediate in cell membranes.
- Copper-resistant cells exhibited fivefold higher acylphosphate formation compared to normal cells.
- Copper-induced relocation of the Menkes ATPase did not affect acylphosphate formation.
- Detailed kinetic and inhibitor sensitivity data were obtained.
Conclusions:
- The Menkes ATPase functions as an active P-type ATPase.
- Acylphosphate intermediate formation serves as a direct functional test for Menkes ATPase activity.
- This research offers insights into copper metabolism and related genetic disorders.