β-oxidation of fatty acids involves the successive cleavage of two-carbon units from acyl-CoA molecules starting at the carboxyl end, forming acetyl-CoA molecules. Several enzymes in the mitochondrial matrix and inner membrane catalyze the oxidation of acyl-CoA to acetyl-CoA, coupling it with ATP phosphorylation. Fatty acids with odd numbers of carbons are oxidized via β-oxidation to produce acetyl-CoA and propionyl-CoA, which is converted to succinyl-CoA for the citric acid cycle. Peroxisomes also perform a modified form of β-oxidation on very long chain fatty acids to form acetyl-CoA and hydrogen per

1. Presentation of bio-chemistry Topic β -OXIDATION OF FATTY ACIDS Submitted to:- Submitted by:- Dr.Zia Ur Rehman Simranjeet kaur B-Pharmacy(5th sem)

2. β -OXIDATION OF FATTY ACIDS INVOLVES SUCCESSIVE CLEAVAGE WITH RELEASE OF ACETYL-CoA In β-oxidation, two carbons at a time are cleaved from acyl-CoA molecules, starting at the carboxyl end. The chain is broken between the α(2)- and β(3)-carbon atoms—hence the name β-oxidation. The two-carbon units formed are acetyl-CoA; thus, palmitoyl- CoA forms eight acetyl-CoA molecules.

4. The Cyclic Reaction Sequence Generates FADH2 & NADH Several enzymes, known collectively as “fatty acid oxidase,” are found in the mitochondrial matrix or inner membrane adjacent to the respiratory chain. These catalyze the oxidation of acyl-CoA to acetyl-CoA, the system being coupled with the phosphorylation of ADP to ATP.

6. Oxidation of a Fatty Acid With an Odd Number of Carbon Atoms Yields Acetyl CoA Plus a Molecule of Propionyl-CoA Fatty acids with an odd number of carbon atoms are oxidized by the pathway of β-oxidation, producing acetyl-CoA, until a three-carbon (propionyl-CoA) residue remains. This compound is converted to succinyl-CoA, a constituent of the citric acid cycle. Hence, the propionyl residue from an odd-chain fatty acid is the only part of a fatty acid that is glucogenic

7. Peroxisomes Oxidize Very Long Chain Fatty Acids A modified form of β-oxidation is found in peroxisomes and leads to the formation of acetyl-CoA and H 2 O 2 (from the flavoprotein-linked dehydrogenase step), which is broken down by catalase.

8. OXIDATION OF UNSATURATED FATTY ACIDS OCCURS BY A MODIFIED β-OXIDATION PATHWAY

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