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Purification of a water-soluble Mg2+-ATPase from human erythrocyte membranes
Abstract:
A water-soluble Mg2+-ATPase previously reported (White, M.D. and Ralston, G.B. (1976) Biochim. Biophys. Acta 436, 567-576) has been purified from human erythrocyte membranes. The purified enzyme has a molecular weight of 575 000; the apparent minimum molecular weight was 100 000, corresponding to a soluble protein of the component 3 region. The Km value for ATP was 1 mM and apparent Km for Mg2+ was 3.6 mM. By means of histochemical activity staining in acrylamide gels it was shown that the purified ATPase preparation could be inhibited by Cd2+ and Zn2+ salts, p-chloromercuribenzoate and N-ethylmaleimide, known inhibitors of membrane endocytosis.
Insights
Researchers purified a water-soluble magnesium-dependent adenosine triphosphatase (Mg2+-ATPase) from human red blood cells. This enzyme, potentially linked to membrane endocytosis, shows specific inhibition patterns with certain metal salts and chemical agents.
Area of Science:
- Biochemistry
- Cell Biology
- Membrane Transport
Background:
- A water-soluble Mg2+-ATPase was previously identified in human erythrocyte membranes.
- Understanding the function and properties of this enzyme is crucial for cellular processes.
Purpose of the Study:
- To purify the water-soluble Mg2+-ATPase from human erythrocyte membranes.
- To characterize the purified enzyme's properties and potential functional associations.
Main Methods:
- Purification of Mg2+-ATPase from human erythrocyte membranes.
- Determination of molecular weight and kinetic parameters (Km for ATP and Mg2+).
- Histochemical activity staining in acrylamide gels to assess inhibitor effects.
Main Results:
- The purified enzyme has a molecular weight of 575,000, with a component 3 region minimum molecular weight of 100,000.
- Kinetic analysis revealed a Km for ATP of 1 mM and for Mg2+ of 3.6 mM.
- The purified ATPase was inhibited by Cd2+, Zn2+, p-chloromercuribenzoate, and N-ethylmaleimide.
Conclusions:
- The purified Mg2+-ATPase is a soluble protein associated with the component 3 region of erythrocyte membranes.
- The observed inhibition patterns suggest a potential role for this ATPase in membrane endocytosis.