B-Oxidation of Fatty acids in Peroxisome

Very Long Chain Fatty acids (VLCFAs) of more than 22-C undergo a preliminary β-oxidation in peroxisomes – the primary site of the synthetase that activates fatty acids of this length.

The shortened fatty acid (16-18-C) diffuses into the mitochondrion for further oxidation linked to carnitine.

In contrast to mitochondrial β-oxidation, the initial dehydrogenation in peroxisomes is catalyzed by a FAD-containing acyl CoA oxidase.

The FADH2 produced is oxidized by molecular oxygen, which is reduced to H2O2.

Therefore, no ATP is generated by this step.

The H2O2 is reduced to H2O by catalase.

Genetic defects in the ability either to target matrix proteins to peroxisomes (Zellweger syndrome, a peroxisomal biogenesis disorder) or to transport VLCFAs across the peroxisomal membrane (X-linked adrenoleukodystrophy), lead to accumulation of VLCFAs in the blood and tissues.