Translocation of Some Anions, Cations, and Acids in Turnip (Brassica napusL.) Mitochondria

The translocation of various anions, cations, and acids across the membrane system of turnip mitchondria has been investigated by light scattering techniques. The results imply that the membranes of turnip mitochondria are not permeable to choline, K⁺, Na⁺, $NH4+$, $CH3CO2-$, $H2PO4-$, and $Fe(CN)63-$. It has been established that Cl⁻, $NO3-$, and SCN− passively permeate the mitochondrial membrane. It is probable that $NH4+$ permeates as NH₃ and that $CH3CO-$ and $H2PO4-$ cross the membrane either as the corresponding acid or on an anion/ hydroxide antiporter. The alkali metals Na⁺ and K⁺ equilibrate across the membrane via specific H⁺/Na⁺ and H⁺/K⁺ antiporters, having similar activity at neutral pH.