Quick Question (Mitochondria)

[kmm5117]

Hello,

First post here, I'm currently taking classes at PSU and have been stumped on this question for quite some time.

There is a substance in the mitochondral membrane, the substance is lipophilic and it is easily protonated and de-protonated what is it and what is it doing.

The possible answers that I thought it could be would be a protein in the electron transport system, although they don't accept protons do they ? To my understanding they only accept electrons form oxidized proteins down the chain and the electron acceptors NAD and FAD.

The other thing I thought it would be was possibly some sort carrier protein for transport through the membrane ?

Thanks in Advance

[coolsheep]

Would it be ubiquinone (CoQ)? That is found in the membrane and is hence lipophillic. It is also involved in the Q-cycle which pumps protons across the mitochondrial membrane. Also it is protonated twice to semiubiquinone and then to ubiquinol.

Coenzyme Q10 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Coenzyme_Q#Chemical_properties)

[student-2]

The transport system in the mitochondrial membrane is a shorter way of saying the ELECTRON transporter complex- they transport electron thus participating in redox reactions. The enrgy of the redox rxns allow proton pumping creating a gradient which is later utilized to create ATP. The last member of this complex utilizes the energy of the gradient by allowing H+ to flow back along its gradient. This energy is coupled to ATP synthesis (hence it's name ATP synthase). I think you may have mixed up some terms with one another.
http://www.stanford.edu/group/hopes/treatmts/ebuffer/f_j13electtrans.jpg