Essay About Yeselectron Source And Ubiquinone Complex Ii

How Does the Reducing Equivalents Go from the Cytoplasm to the Mitochondrion?
How does the reducing equivalents go from the cytoplasm to the mitochondrion? They don’t cross the membrane, but electrons do through two ways:Glycerol 3-phosphate shuttle:In cytoplasm, DHAP is reduced to glycerol 3-phospahe by NADH. Enzyme: cytoplasmic Glycerol 3-phoshate dehydrogenase.FAD is reduced to FADH2 in the enzyme called mitochondrion Glycerol 3-phoshate dehydrogenase. FAD is prosthetic group in the enzyme.Ubiquinone (Q) is reduced to Ubiquinol (QH2)Malate-Aspartate shuttle:In cytoplasm, OAA + NADH → Malate + NAD+. Enzyme: cytoplasmic Malate dehydrogenase.Malate is transported into the MatrixMalate + NAD+ → OAA + NADH. Enzyme: Mitochondrial Malate dehydrogenase.Glutamate is transformed to a-Ketoglutarate , and OAA is transformed to Aspartate. Enzyme: Mitochondrion Aspartate amino transferase. Glu+ OAA → Asp + a-ketoglutarate.Asp + a-ketoglutarate are transported to the cytoplasm.Asp + a-ketoglutarate → Glu+ OAA. Enzyme: cytoplasmic Aspartate amino transferase.The more negative Eo, the greater the electron-transfer potential and the greater the tendency to donate electrons. The more positive Eo, the greater the greater the tendency to accept electrons.————————————————————————————————————Electron Transport Chain: Integral proteinsComplex I (NADH-Q oxidoreductase, NADH dehydrogenase):Pumps protons? YesElectron source: NADHElectron carriers: FMN – multiple Fe-S centersUltimately reduce: Ubiquinone Complex II (Succinate-Q reductase, succinate dehydrogenase):Pumps protons? NoElectron source: SuccinateElectron carriers: FAD – multiple Fe-S centersUltimately reduce: UbiquinoneComplex III (Q-cytochrome C oxidoreductase):Pumps protons? YesElectron source: UbiquinolElectron carriers: 3 cytochromes– Rieske Fe-S centersUltimately reduce: Cytochrome CComplex IV (Cytochrome C oxidase):Pumps protons? YesElectron source: cytochrome CElectron carriers: CuA/cytochrome a- CuB/cytochrome a3Ultimately reduce: O2Ubiquinone (oxidized) / Ubiquinol (reduced)Hydrophobic; travels within the inner membraneAccepts electrons from G3P, complex I, and complex II.Carries electrons to complex III.There is semiquinone intermediate.Cytochrome C Hydrophilic; travels within the intermembrane space.Accepts electrons complex IIICarries electrons to complex IV.————————————————————————————————————Complex III has 3 cytochromes that contain hemes: bH, bL, c1. Electrons are transported from one Fe to another until reaching rieske Fe-S center. They are coordinated by cysteines and histidines.In complex IV:2 cytochromes C transfers electrons to reduce CuB/heme a3reduced CuB/heme a3 bind oxygen to form peroxide bridge.2 electrons and 2 protons cleaves the bridge.2 more protons release the waterthere are histidine and tyrosine adducts————————————————————————————————————Mitochondrial ATP synthasome:ATP synthaseATP/ADP antiporterInorganic phosphate transporterATP synthase has two regions:F0: region in which protons flow.F1: the site of ATP synthesis using rotational energy.Rotating components:C rings: contains Apartate/ Aspartic acidγ: central shaft; asymmetric; cause change in β subunits when rotating  εStationary components:Stator:a: cytoplasmic half channel/matrix half channelb2δHexameric ring:α3: for structureβ3: site of ATP synthesis Conformations in β subunits:Open: ADP and P are bound; ATP is releasedLoose: ADP and P are boundTense: ATP is synthesized.