A major source of cellular energy production, in the form of ATP, is derived from the proton motive force supplied to mitochondrial ATP synthase. The main driver of the proton gradient across the inner mitochondrial membrane is the electron transport system. NADH and FADH2 produced by glycolysis, fatty acid oxidation and the TCA cycle serve as a electron donors and cofactors for the protein complexes involved in the electron transport system. The net result is an influx of protons into the intermembrane space of the mitochondria and the production of water as a byproduct in the inner mitochondrial membrane.
2 H+ + 2 e+ + 1/2 O2 → H2O + energy
There are four membrane-bound protein complexes that participate in the electron transport system.
ATP Synthase is often termed Complex V of the electron transport system since it uses the proton motive force of the translocated protons to drive the nanomotor, which condenses ADP and phosphate to form ATP in the matrix.
Cytochrome c: Our Cytochrome c products are supplied mainly in the oxidized form of the protein. The reduced form of cytochrome c can be prepared with either sodium dithionite or sodium ascorbate, followed by gel filtration. (See Dixon, H.B., and McIntosh, R., Nature, 213(74), 399-400 (1967))
We employ two methods for purification of cytochrome c; either trichloroacetic acid (TCA) is used during preparation or acetic acid. The "TCA" procedure may reduce the amount of superoxide dismutase (SOD), but tends to cause dimerization or "acid-modified structures." In contrast the "acetic acid" method may have slightly higher amounts of SOD, but a lower percentage dimeric cytochrome c. Ion-exchange chromatography is used during purification. Any SOD present can readily be removed using size exclusion chromatography.