Existence of two distinct Hipip-type iron-sulfur centers in mitochondria.

Two distinct Hipip type iron-sulfur centers are present in pigeon heart mitochondria. These two can be distinguished by their EPR spectra which differ in the detailed line shape, field position and temperature dependence. These two seem to correspond to Center S-3, and an iron-sulfur protein purified by Ruzicka and Beinert. They exhibit different thermodynamic behavior and topographical location in the mitochondrial membrane.