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Modification of the Rate of Ouabain Binding to (Na + + K + )ATPase by Lithium Ions
Author(s) -
Krishnan Nagaswamy,
Albers R. Wayne
Publication year - 1980
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1980.tb03719.x
Subject(s) - ouabain , lithium (medication) , chemistry , binding site , ion , biophysics , stereochemistry , atpase , enzyme , biochemistry , sodium , endocrinology , biology , organic chemistry
: We report on the interactions of Li + , a congener of K + with the (Na + + K + )‐ATPase from E Electricus as measured by their effects on the rate of [ 3 H]‐ouabain binding to this enzyme. Like K + , Li + slows ouabain binding under both Type I (Na + + ATP) and Type II (P i ) conditions, but with lower affinity. In contrast to K + , the Li + inhibition curve is hyperbolic, suggesting interaction at an uncoupled site. Also differing from the complete inhibition by high K + , a residual ouabain‐binding rate persists at high Li + . The interactions of Li + and K + are synergistic: the apparent K + affinity increases 3 to 4‐fold in presence of Li + . These results are consistent with the conclusion that Li + interacts with only one of the two K + sites and may be of interest in interpreting lithium pharmacology.