Affiliation:
1. Vinča Institute of Nuclear Sciences, Laboratory of Physical Chemistry, Belgrade
2. Faculty of Chemistry, Belgrade
Abstract
The influence of Co 2+ ions on the activities of Na+/K+-ATPase and Mg2+
-ATPase, enzymes from rat brain synaptic plasma membrane, was studied. The
aim of this study was to investigate the inhibition of both ATPases
activities byexposure tocobalt ions as a function of experimentally
added CoSO4. The "free" Co2+ concentrations in the reaction mixturewere also
calculated and discussed. CoSO4 induced a dose-dependent inhibition of both
enzymes. The IC50 values of Co 2+, as calculated from the experimental
curves, were 168 mM for Na+/K+-ATPase and 262 mMfor Mg 2+-ATPase, and
for the recalculated free Co 2+ concentration 75.4 mM for Na+/K+-ATPase
and 136 mM for Mg 2+-ATPase. The obtained linear Dixon's plot for
Na+/K+-ATPase implies equilibium binding of cobalt with inhibitory sites
on the enzyme. The kinetic parameters for both enzymes in presence and
absence of CoSO4 were calculated from the experimental data. The results of
the kinetic analysis show that inhibition of Na+/K+-ATPase induced by
CoSO4 is non-competitive, and for Mg 2+-ATPase that there are two sites of
different sensitivities or two different enzymes.
Publisher
National Library of Serbia
Cited by
8 articles.
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