Oxidation of Fatty Acids Flashcards

Beta Oxidation Overview

• Beta oxidation is a catabolic process that breaks down fatty acids into acetyl-CoA, NADH, and FADH2 in the mitochondria.
• Acetyl-CoA enters the citric acid cycle, while NADH and FADH2 are utilized in the electron transport chain.
• The process occurs mainly in the mitochondrial matrix.

Products and Importance

• Products of beta oxidation include acetyl-CoA and the coenzymes NADH and FADH2, crucial for energy metabolism.
• Each palmitoyl CoA molecule undergoes seven cycles of beta oxidation, yielding 8 acetyl-CoA molecules.

Steps in Beta Oxidation

• FA activation involves esterification with CoA in the cytoplasm, forming fatty acyl-CoA via acyl CoA synthetase.
• Mitochondrial uptake requires a transport mechanism facilitated by carnitine, with CPT1 and CPTII enzymes facilitating the exchange of CoA and carnitine.
• The overall reaction sequence includes dehydrogenation, hydration, more dehydrogenation, and carbon-carbon cleavage.

Special Cases in Fatty Acid Oxidation

• Unsaturated fatty acids undergo normal beta oxidation until a double bond is encountered, requiring isomerization to continue.
• Polyunsaturated fatty acids similarly require multiple isomerizations to complete the oxidation process.
• Odd carbon fatty acids produce succinyl-CoA after normal beta oxidation cycles, allowing entry into the TCA cycle.

Peroxisomal Oxidation

• Very long-chain fatty acids are oxidized in peroxisomes until they are short enough (8 carbons) to be transported into mitochondria.
• NADH and FADH2 generated in peroxisomes do not participate in oxidative phosphorylation but instead produce hydrogen peroxide.
• Hydrogen peroxide is subsequently converted into water and oxygen through enzymatic action.

Enzymes Involved

• Key enzymes include acyl CoA synthetase for activation, CPT1 for mitochondrial uptake, and dehydrogenases for various steps within beta oxidation.
• Isomerases and mutases are crucial for modifying unsaturated and odd carbon fatty acids.

Energy Yield from Beta Oxidation

• Each cycle of beta oxidation generates 5 ATP (2 from FADH2 and 3 from NADH) through oxidative phosphorylation.
• The metabolic efficiency of β-oxidation contributes significantly to ATP production, supporting various cellular functions.