70 90 Stage 1 oxidation of fatty acids

70 -90%

• Stage 1: oxidation of fatty acids, glucose, and some amino acids yields acetyl Co. A. • Stage 2: oxidation of acetyl groups in the citric acid cycle includes four steps in which electrons are abstracted • Stage 3: Electrons carried by NADH and FADH 2 are funneled into a chain of mitochondrial electron carriers--- the respiratory chain--- reducing to O 2 to H 2 O-- for production of ATP

• Pyruvate Dehydrogenase Complex • Location: mitochondrion

Enzyme Abbreviation Number of chains Prosthetic group Reaction catalyzed Pyruvate dehydrogenase component E 1 24 TPP Oxidative decarboxylation of pyruvate Dihydrolipoyl transacetylase E 2 24 Lipoamide Transfer of the acetyl group to Co. A Dihydrolipoyl dehydrogenase E 3 12 FAD Regeneration of the oxidized form of lipoamide

70 -90%

The fatty acid, palmitate

Final common pathway for the oxidation of fuel molecules • Amino Acids • Fatty Acids • Carbohydrates

Sir Hans Krebs – first formulated its reaction into a cycle Citrate was one of the first compounds to participate Tricarboxylic acid cycle Tricarboxylic acid – citrate and isocitrate

3 molecules of NADH 1 molecule of FAD(2 H)

oxidation decarboxylation

Acetyl-Co. A + 3 NAD + FAD + GDP + Pi + H 2 O 2 CO 2 + 3 NADH + FADH 2 + GTP + 2 H+ +Co. A

Glycolysis Fatty Acid Oxidation Citric Cycle NADH FADH 2 (with a pair of electrons each) • Electrons are used to reduce molecular oxygen to water • Free energy is used to generate ATP = OXIDATIVE PHOPHORYLATION

2 NADH

NADH can not penetrate the inner mitochondrial membrane 1. Glycerol-3 -phosphate shuttle 2. Malate-asparate shuttle

Oxidative Phosphorylation; Electron Transfer Chain • mitochondria; inner membrane (in contrast to TCA cycle – matrix of mitochondria) • Series of oxidation-reduction reactions; NADH and FADH 2 are used to reduce molecular oxygen; exergonic reduction are used to generate ATP • Electron transfer reactions – set of integral membrane proteins and cofactors (which can freely diffuse across membrane) • Complex I, III, IV : at these steps energy from electron (e-) transfer can be used for pumping H+ into the intermembrane space • Complex II: tranfer of electron from FADH 2 ( derived from succinate dehydrogenase) to Coenzyme Q NADH yields FADH 2 yields 2. 5 to 3 ATP 1. 5 to 2 ATP