Alpha oxidation of fatty acid

Alpha oxidation

         α-oxidation is a process in which fatty acid are shortened by one carbon atom. α-oxidation was 1st observed in seeds and leaf tissues of plant. The original substrate has been demonstrated in the microsomes of brain and liver and tissues also. Involves decarboxylation process for the removal of single carbon atom at one time with the resultant production of odd chain fatty acids that can be subsequently oxidized by β-oxidation for energy production. It is strictly an aerobic process. The process involves hydroxylation of the α carbon with a specific α-hydroxylase that requires fe++ and vitamin C/FH4 as co-factor.  Hydroxy fatty acids can be converted to the α-keto acid, followed by oxidative decarboxylation resulting in the formation of long chain fatty chain with an odd number of carbon atoms.The initial hydroxylation reaction is catalyzed by a mitochondrial enzyme, monoxygenase that requires O2, Mg²⁺, NADPH and heat stable co-factor.  Normally metabolized by an initial α-hydroxylation followed by dehydrogenation and decarboxylation. Whole reaction produces 3 molecule of propionyl CoA, 3 molecules of acetyl CoA, and 1 molecule of iso-butyryl CoA.

Biological significance of Alfa oxidation

·         α-oxidation is most suited for oxidation of phytanic acid, produced from dietary phytol.
·         Phytanic acid is a significant constituent of milk lipids and animal fats.
·         Enzymatic deficiency in α-oxidation leads to Refsum’s disease.

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