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. FADH2 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
Intermembrane Glycerol glycerol space 3-phosphate 3-phosphate Ubiquinone(Q) cytosolIc) dehydrogenase accepts electrons FAD nnnn'nniminnnrinln from both NADH Fe-S Q land FADH, in the I FMN respiratory chain Fe-S FAD (FAD) NADH NAD+ ETF: Q Succinate oxidoreductase ETF (FAD) Matrix acyl-CoA dehydrogenase FAD Fatty acyl-CoA
Ubiquinone (Q) accepts electrons from both NADH and FADH2 in the respiratory chain
5. Electrons of QH, is transferred to cytochrome c via ubiquinone: cytochrome c oxidoreductase(complex ID) Also called cytochrome c reductase or cytochrome bcr complex a 250 kD multiprotein complex of ll subunits Complete 3-D structure was determined in 1997! The functional core consists of three subunits cytochrome b(with two hemes, bH and 61): an Fe-S protein; and cytochrome c, (with the heme group covalently bound to protein via two thioether bonds)
5. Electrons of QH2 is transferred to cytochrome c via ubiquinone:cytochrome c oxidoreductase (complex III) • Also called cytochrome c reductase or cytochrome bc1 complex. • A 250 kD multiprotein complex of 11 subunits. • Complete 3-D structure was determined in 1997! • The functional core consists of three subunits: cytochrome b (with two hemes, bH and bL ); an Fe-S protein; and cytochrome c1 (with the heme group covalently bound to protein via two thioether bonds)
TwO-electron carrier QH, passes one electron to the one-electron carrier Fe-s center. then to the heme c group in Cyt C1, and finally to the heme C group of Cyt c, the other electron to b, bH, and finally to an Q or Q. via a so-called"Q cycle Cytochrome c, a soluble protein located in the intermembrane space, will move to complex IV
• Two-electron carrier QH2 passes one electron to the one-electron carrier Fe-S center, then to the heme C group in Cyt c1 , and finally to the heme C group of Cyt c; the other electron to bL , bH, and finally to an Q or Q. - via a so-called “Q cycle”. • Cytochrome c, a soluble protein located in the intermembrane space, will move to complex IV