In this disease, known as Refsum's Disease , the patient is unable to metabolize phytanic acid , a fatty acid that is derived from chlorophyll, and that must be metabolized by alpha oxidation. This disorder results in an accumulation of phytanic acid, which is toxic in high concentrations. The second minor oxidative pathway for fatty acids is the omega oxidation pathway . Oxidation of this alcohol then produces a dicarboxylic acid , which can be oxidized on both ends by beta oxidation. The results of this process are short chain dicarboxylic acids which can enter the Krebs cycle.
Omega oxidation is important in the metabolism of drug molecules which contain alkyl chains.
These molecules can be converted to carboxylic acids by omega oxidation, and are thus made more polar, facilitating their excretion. When fatty acid metabolism becomes predominent in the cell, a significant proportion of acetyl CoA is shuttled into a pathway known as ketogenesis . When acetyl CoA is present in high amounts, the beta-ketothiolase reaction is reversed, forming large quantities of acetoacetyl CoA . This intermediate then reacts with acetyl CoA in a process mediated by HMG CoA synthase to produce HMG-CoA, an intermediate in cholesterol biosynthesis. Acetone, beta-hydroxybutyric acid and acetoacetic acid are collectively known as the ketone bodies .