Sodium Ion Influences on Phosphorylations Associated with Oxidation of Succinate by Turnip Root Mitochondria

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Science  19 Apr 1968:
Vol. 160, Issue 3825, pp. 304-306
DOI: 10.1126/science.160.3825.304


Sodium ions (10-3 mole/liter) cause a marked increase in the ratio of phosphate esterified to oxygen utilized when turnip root mitochondria oxidize succinate. Separate study of the two phosphorylation sites associated with succinate oxidation indicates that the observed effect is a summation of differential responses of these sites to sodium ions. The activity of the first site, that associated with the reduction of cytochrome c, is stimulated about threefold by 10-3 molar NaCl, whereas phosphorylation at the second site, coupled with the oxidation of ferrocytochrome c, is slightly inhibited by the same concentration of NaCl.

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