Figure 1.

Cardiolipin structure. The figure depicts (for simplicity only) one of the cardiolipins–tetraoleilcardiolipin, and the two models headgroup ionization state at physiological pH 7.2. (a) Both phosphates have values of pK_a1 of orthophosphoric acid. It is assumed that both phosphates ionize independently and the headgroup exists as a dianion. (b) Disparate pKa values of the two phosphates presume that the headgroup exists as a monoanion. The figure was adapted from [27]. Note: values for dissociation constants (pKa) of orthophosphoric acid: pK_a1 = 2.15, рК_а2 = 7.20, ирК_а3 = 12.35.