Question

For Both DNP and Oligomycin

- what does it bind to/where at, explain what effect if any it will have on the "flow" of e-down the ETC, explain any impact on the apparent consumption of oxygen, explain any impact on the PMF and explain an impact on the ATP production?

Answer 1

Dinitrophenol (DNP) is an uncoupler. It uncouples ETC from oxidative phosphorylation leading to proton leak across the inner mitochondrial membrane.

DNP binds to protons on the mitochondrial intermembrane space and moves them to mitochondrial matrix.

Effect on ETC: DNP increases ETC. This because DNP’s uncoupling action reduces ATP production. This low levels of ATP leads increased metabolism and electron flow down ETC.

Effect on oxygen consumption: DNP increases oxygen consumption due to increased ETC.

Effect on PMF: DNP reduces proton motive force (PMF) gradient as it helps dissipating H+ ions across the membrane to matrix bypassing ATP synthase.

Effect on ATP production: DNP reduces ATP production as it helps dissipating H+ ions across the membrane to matrix bypassing ATP synthase.

Oligomycin binds to and inhibits ATP synthase (F0 unit).

Effect on ETC: Similar to DNP, oligomycin too increases ETC. This because inhibition of TAP synthase by oligomycin reduces ATP production. This low levels of ATP leads increased metabolism and electron flow down ETC.

Effect on oxygen consumption: Oligomycin increases oxygen consumption due to increased ETC

Effect on PMF: Oligomycin increases PMF gradient as it blocks ATP synthase which is now unable to pump the protons across the membrane from intermembrane space to mitochondrial matrix.

Effect on ATP production: Oligomycin reduces ATP production as it blocks ATP synthase.