The eccentric Complex II of the mitochondrial respiratory chain

Complex II, otherwise termed Succinate-coenzyme Q reductase is an exotic member of the electron transport chain at least in 3 ways: unlike the other enzymes it is part of the TCA-Krebs-Szentgyörgyi cycle too due to its succinate dehydrogenase subunit , not any subunits of the complex are encoded by the mitochondrial DNA and it is not involved in proton pumping does not contain a proton pump that translocate protons from the matrix to the intermembrane space.

complexII

4 thoughts on “The eccentric Complex II of the mitochondrial respiratory chain

  1. Disagree that it is not involved in proton pumping. While strictly it does not contain a proton pump (like complex I or 4), it uses Q to make QH2. Where do the protons to make QH2 come from? The matrix. Where do they end up when the QH2 gets oxidised by complex III? On the outside. So, by virtue of its generating QH2, it does kinda participate in proton pumping, but only half-way. You need complex II and III together to get a complete proton translocation event.

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