Inactivation of Nа+, К+-АТРase from cattle brain by sodium fluoride
The influence of the physiological ligands and modifiers on the plasma membrane Na+, K+-ATP-ase from calf brain inactivation by sodium fluoride (NaF) is studied.
ATP-hydrolyzing activity of the enzyme was found to be more stable as to NaF inhibition than its K+-pNPPase activity. The activatory ions of Na+, K+-ATPase have different effects on the process of the enzyme inhibition by NaF. K+ intensifies inhibition, but Na+ does not affect it. An increase of [Mg2+free] in the incubation medium (from 0.5 to 3.0 mM) rises the sensitivity of Na+, K+-ATPase to NaF inhibition. But an increase of [ATP] from 0.3 to 1.5 mM has no effect on this process. Ca and Mg ions modify Na+, K+-ATPase inhibition by fluoride differently. Ca2+free levels this process, and Mg2+free on the contrary increases it.
In the presence of Ca ions and in the neutral-alkaline medium (pH 7.0–8.5) the recovery of activity of the transport ATPase inhibited by NaF takes place. Sodium citrate also protects both ATP-hydrolizing and K-pNPPase activity of the Na+, K+-ATPase from NaF inhibition.
Published at the site: 2004-02-02
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