Oxidative phosphorylation - wou.eduguralnl/gural/450Oxidative phosphorylation.pdf · Oxidative phosphorylation • Chemiosmotic coupling hypothesis • Proton motive force • Production

Oxidative phosphorylation• Chemiosmotic

coupling hypothesis• Proton motive force• Production of ATP• NADH from

Glycolysis• Total ATP • Transport of ATP • Rates of Respiration

Chemiosmotic coupling hypothesis

• Peter Mitchell • Movement of H+

across inner membrane produces gradient

Proton motive force

• Two components – membrane potential – pH gradient

• Calculate gradient using equation – pH gradient 1.4 units

in liver and E. coli• 12 H+ pumped out/

pair of electrons

Proton motive force

ATP synthase in inner membrane

• Two components • F1 stalk, matrix of

mitochondria

• Fo in membrane

F1 stalk, matrix of mitochondria

• Α3, β3, γ,δ,ε subunits: β interacts with γ.• T(tight) = binds ATP• L (loose) = ADP & Pi• O (open) = bound or release nucleotide• Rotation of γ subunit due to movement of protons

through Fo

Fo in membrane

• Fo hydrophobic, proton channel• a subunit and c rings (10-14 rings)• H+ enters cytosolic channel neutralize aspartic acid• c ring rotates• H+ leaves matrix channel, aspartic acid charged• repeat

Production of ATP

• 2.5 ATP/NADH • 1.5 ATP/FADH • How much ATP? • Pyruvate to Acetyl

CoA • TCA cycle

NADH from GlycolysisGlycerol 3-P shuttle Malate-aspartate shuttle

Total ATP

• Glycolysis and TCA cycle

• Efficiency compared to just glycolysis

Transporters

• ATP/ADP exchange • Pi/OH- exchange

Rates of Respiration

• O2 consumption versus time

• Addition of ADP needed

• calculate P/O ratio of different compounds

Respiration rates

Respiration--Uncouplers

• Uncouplers and their effect

• DNP • vallinomycin• gramicidin