ElectronTransport&OxidativePhosphorylation

Dr.KevinAhern

Biological Energy

Oxidation

Reaction Catalyzed by Glyceraldehyde-3-phosphate Dehydrogenase

OxidizedReduced

Oxidation of NADH

Electrical and Chemical Potential

The Nernst Equation

Overall, ΔG = -nFΔE

Electron Transport

Inner Mitochondrial

Membrane

Complex II

Reaction

Electron Movement

Ubiquinone

Ubiquinol

2e- + 2H+

Complex III

Cytochrome C

Small, mobile peripheral protein Inner mitochondrial membrane Shuttles electrons between complexes III and IV Very conserved across all living systems

Note

Note Note

Alternative Oxidase Pathway of Plants, Fungi, Protozoa

Short-circuits System

Requirements for Electron Transport

1. Electron carriers (NADH/FADH2) 2. Oxygen

Electron Transport Inhibitors

Complex I Complex I Complex III

Rotenone Amytal Antimycin A

Cyanide Carbon Monoxide

Azide

Inhibit Inhibit Inhibit

Reactive Oxygen Species

Reactive Oxygen Species

1. Non-enzymatic reactions 2. Damaging to cells

Superoxide + Nitric Oxide Peroxynitrite

NO(O2-)

Reactive Oxygen Species - Cellular Protection

1. Antioxidants a. Glutathione b. Vitamins A, C, E c. Uric acid 2. Enzymes a. Catalase b. Superoxide Dismutase

Catalase

Glutathione

Reduced Form Oxidized Form

Superoxide Neutralization

Superoxide Dismutase

Oxidative Phosphorylation

Mitchell’s Chemiosmotic Process

1. Intact inner mitochondrial membrane 2. Movement of electrons “pumps” protons 3. Proton gradient drives formation of ATP

Electron Transport

Oxidative Phosphorylation

ATP Synthase (Complex V)

ATP Synthase (Complex V)

Oxidative Phosphorylation Requirements

1. Proton Gradient 2. ADP

Oligomycin - ATP Synthase Inhibitor

Respiratory Control

1. Tightly coupled vs. Uncoupled 2. Requires intact mitochondrial inner membrane 3. ETS and oxidative phosphorylation are interdependent 4. Stopping either will stop the other

Respiratory Control

2,4 Dinitrophenol (2,4 DNP)

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