Answer to Question #212632 in Biochemistry for fgjhj

Question

List the similarities and differences between peroxisomal and mitochondrial fatty acid oxidation

Answer 1

β-Oxidation occurs in both mitochondria and peroxisomes.

Similarities:

1. Both peroxisomes and mitochondria contain a beta-oxidative pathway
2. The overall pathways are essentially the same in both mitochondria and peroxisomes: Fatty acids are first activated as acyl-CoA and then the activated fatty acid (acyl-CoA) is dehydrogenated. This represents the first step of beta-oxidation. Hydration of the double bound then occurs, and is followed by dehydrogenation and cleavage. This allows for the removal of 2 C from C:n acyl-CoA, leading to the formation of C:n-2 acyl-CoA.

Differences:

1. Mitochondria catalyze the β-oxidation of the bulk of short-, medium-, and long-chain fatty acids. Peroxisomes are involved in the β-oxidation chain shortening of long-chain and very-long-chain fatty acyl-coenzyme (CoAs), long-chain dicarboxylyl-CoAs, the CoA esters of eicosanoids, 2-methyl-branched fatty acyl-CoAs, and the CoA esters of the bile acid intermediates di- and trihydroxycoprostanoic acids
2. End products for mitochondria is Acetyl-CoA (and subsequently ATP), for peroxisomes is Acetyl-CoA and medium-chain fatty acids (and subsequently H202)
3. In yeasts and plants, fatty acid oxidation occurs uniquely in peroxisomes, as mitochondria are not able to catabolize fatty acids. 
4. Entry system for mitochondria is the carnitine system (including CPT1, CACT and CPT2), for peroxisomes is ABC transporters.
5. Physiological implications for mitochondria is energy production, for peroxisomes is the biosynthesis of specific fatty acids (e.g., Docosahexaenoic acid)