Question

Acyl-CoA dehydrogenase deficiencies are diseases related to the impaired ability to oxidize fatty acids via beta oxidation. Symptoms of these acyl-CoA dehydrogenase deficiencies include hypoketosis [low blood levels of ketone bodies], hypoglycemia [low blood glucose], and hyperammonemia [increased blood levels of ammonia] during long periods of fasting.

In what 2 ways is beta oxidation important during prolonged periods of fasting?

(BioChem)

Answer 1

Beta oxidation produces Acetyl CoA. Beta oxidation is the process where fatty acids are converted in to acetyl CoA. The molecule Acetyl CoA can enter in to Krebs cycle to genetare energy. Wehn a person is fasting, levels of glucose are lower. So for producing energy, Gluconeogenesis is  used. Fatty acids that are stored in adipose tissue are one such source of energy. These fatty acids under go beta oxidation int he mitochondria of liver cells to produce acetyl CoA.

The process includes: First fatty acids are activated by Acyl CoA synthase in to Acyl CoA in th epresence of ATP and CoA-SH. The Acyl CoA is transported in to mitochondrial matrix by Carnatene shuttle. Inside the matrix Fatty Acyl CoA is dehydrogenated by Acyl CoA dehydrogenase to form Trans Enoyl CoA. During the process one FADH is formed. This is the beginning of the process of betaoxidation. So lack of this enzyme will prevent the process of beta oxidation. Large number of Actyl Co A molecules formed by beta oxidation to fuel the Krebs cycle and provide huge amount of energy. So Beta oxidation is important during fasting.

Fatty acids break down also produce ketone bodies. Acetoacetate and acetone are the important ketone bodies. Ketone bodies are another source of energy to the cells of the body. Ketone bodies are small water soluble molecules which readily enter in to cells and get converted in to Acetyl CoA. The Acetyl CoA enters in to Krebs cycle for generating energy.