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Effect of nitroso compounds on Na/K-ATPase
A A Boldyrev1, E R Bulygina, G G Kramarenko
1Department of Biochemistry, School of Biology, International Biotechnological Center of M.V. Lomonosov Moscow State University, Russia. aab@atpase.bio.msu.su
Biochimica Et Biophysica Acta
|December 11, 1997
Summary
Nitric oxide (NO) derivatives, particularly dinitrosyl iron complexes (DNIC), inhibit brain and kidney Na/K-ATPase by blocking essential thiol groups. This disruption affects enzyme activity and inter-subunit interactions.
Area of Science:
- Biochemistry
- Enzymology
- Physiology
Background:
- Na/K-ATPase is a crucial ion pump in cell membranes.
- Nitric oxide (NO) and its derivatives can modulate enzyme activity.
- The role of NO derivatives in regulating Na/K-ATPase is not fully understood.
Purpose of the Study:
- To investigate the inhibitory effects of thiol-containing NO derivatives on brain and kidney Na/K-ATPase.
- To elucidate the mechanism underlying the inhibition of Na/K-ATPase by NO derivatives.
Main Methods:
- Enzyme activity assays for Na/K-ATPase from brain and kidney.
- Treatment with S-nitrosoglutathione and dinitrosyl iron complexes (DNIC) with cysteine or glutathione.
- Measurement of protein thiol groups.
- Analysis of substrate dependence curves.
- Enzyme activity restoration using dithiothreitol or cysteine.
Main Results:
- Dinitrosyl iron complexes (DNIC) with cysteine or glutathione significantly inhibited Na/K-ATPase activity.
- Brain Na/K-ATPase was more sensitive to inhibition than kidney Na/K-ATPase.
- Inhibition correlated with a decrease in protein thiol groups and altered substrate dependence.
- Enzyme activity and thiol groups were restored by SH-reagents.
Conclusions:
- Blockade of Na/K-ATPase thiol groups by NO derivatives is responsible for enzyme inhibition.
- Inhibition may involve disruption of inter-protomer interactions in the enzyme complex.
- NO derivatives could play a regulatory role in Na/K-ATPase function.