Redox Coupling: the energy released by the oxidation of NADH to NAD, allows for the proton pump to
pump into the intermembrane space. Proton conc. is higher in the intermembrane space, and has a
lower pH. There are 4 complexes in the chain. 1,3,4 are the 3 complexes that pump protons. The free
energy from succinate to fum arate is not enough to pump a proton, this happens at 2.
NADH: coQ reductase. Catalyzes transfer of electron from nadh to coq. NADH + coq + 2h - > nad + h +
coqH2. The 2 electrons and one proton is first transferred to flavin, a triple ring compound. Exists as a
monomer in complex 1. 9 iron-sulfur centres are part of complex 1. 7 of which are involved in the
electron transfer. Ferric to the ferrous state and then passed on. 4 protons pumped for every nadh
Succinate: coq reductase (complex II). Succinate and CoQ becomes fumarate and coqh2. No proton
pumped by this complex.
CoQH2 – cytochrome c reducase (complex III): QH2 diffuse through the membrane to 3, which the
ncatalyzes the transfer of electrons from qH2 to cytochrome c. Cytochrome c is a small mobile and
water soluable electron carrier, which moves on the outer surface of the inner membrane. Cytochromes
have 2 other forms, which are embedded in the membrane. They are redox carriers with bound heme.
C-type has covalently bound cytochrome