• convert E'o to deltaG.
• deltaGo' = - nFE'o
• n = # electrons transferred, F = faraday's contant

• electrons come from NADH and FADH2.
• mobile e- carriers ubiquinone and cytochrome c connect the complexes.
• electrons move toward positive reduction potential.
• protons are pumped from matrix into cytosol side of inner membrane

• Q: 2 keto groups can accept H+.
• QH: semiquinone intermediate.
• QH2: ubiquinol

• heme group in center.
• carries one e-.
• transfers b/w complex III and IV

• NADH:Q oxidoreductase.
• very large, located in matrix and inner membrane.
• QH2 gets one H and 2 electrons from each NADH (passes through FMN and Fe-S) and one from 5H+ in the matrix.
• other 4 H+ pumped into intermembrane space.

• succinate:Q reductase.
• Electrons flow directly from succinate to a covalently bound FAD.
• succinate dehydrogenase is part of this complex.
• Iron sulfur proteins transfer electrons from FADH2 to Q.
• NO protons are pumped

Q:cytochrome c oxidoreductase.

Four tightly bound prosthetic groups:

• cytochrome b: contains two heme groups bL and bH
• Reiske Iron sulfur cluster
• cytochrome c1 delivers electrons one at a time to cytochrome c

• Cytochrome c oxidase.
• reduces molecular oxygen.
• 3 subunits: heme a and a3, CuA and CuB