CH3 Ubiquinone is a mobile CH3O (CH2-CH=C—CH2)10-H Ubiquinone (@) electron/proton carrier (fully oxidized) CH3O CH3 ● Fat soluble CH+e benzoquinone with a very long isoprenoid side CH3O R Semiquinone radical chain; can accept one or (QH) CHO CH3 two electrons, forming OH radical semiquinone or H+e ubiquinol (qh2): QH OH diffuses to the next CHO R Ubiquinol(QH2) complex(li; the only (fully reduced) CH3O CH3 electron carrier not OH bound to a protein
•Fat soluble benzoquinone with a very long isoprenoid side chain; can accept one or two electrons, forming radical semiquinone or ubiquinol (QH2 ); QH2 diffuses to the next complex (III); the only electron carrier not bound to a protein. Ubiquinone is a mobile electron/proton carrier
4. FADH, of flavoproteins also transfer their electrons to ubiquinone Flavoproteins like succinate dehydrogenase (complex D), fatty acyl-CoA dehydrogenase, and glycerol 3-phosphate dehydrogenase are associated to the inner membrane of mitochondria and transfers their electrons collected on FADH, toO to form QH The energy released from these electron transferring is not high enough to promote proton pumping
4. FADH2 of flavoproteins also transfer their electrons to ubiquinone • Flavoproteins like succinate dehydrogenase (complex II), fatty acyl-CoA dehydrogenase, and glycerol 3-phosphate dehydrogenase are associated to the inner membrane of mitochondria and transfers their electrons collected on FADH2 to Q to form QH2 . • The energy released from these electron transferring is not high enough to promote proton pumping