The effects of electrolytes on the interaction of cationic dyes with energized mitochondrial fragments.

Abstract

The binding of cationic dyes to energized submitochondrial particles and the extent and rate of absorbance changes accompanying the binding are enhanced by the presence of inorganic anions. The anion effect follows the sequence: SCN‐ > ClO4− > I‐ > NO3− > Br‐ > Cl− > BrO3−= H2PO4− > CH3COO− > F−. With the more lipophilic anions the phase of enhancement is followed by one of inhibition: this effect is more marked with more lipophilic dyes. The rate and extent of absorbance changes is also affected by cations according to the sequence: Ba2+ > Sr2+ > K++ valinomycin > Li+ > Mg2+ > Ca2+ > Cs+∼ Rb+∼ K+∼ Na+. Under conditions where the anions markedly enhance the binding of the dyes by the energized fragments there is no parallel increase of anion binding. It is suggested that the membrane conformation and therefore the accessibility of the sites for various ligands, is modified during the interaction of electrolytes with energized fragments.