It is well-known that the coupling between Q reduction and proton pumping is such that the point mutations in the distal membrane arm of complex I can severely inhibit Q redox activity (section 1). However, one can envisage that the energy released in the first few cycles of slow NADH oxidation (and Q reduction) in the D state may not be coupled to proton pumping. If so, the question is what happens to ca. 800 meV energy released upon Q reduction in these initial turnovers. Here, we suggest that part of this energy is utilized for the protonation of E channel region of complex I.