Acyl-CoA dehydrogenase

• 
  Diagram of the beta-oxidation pathway
• 
  Structure of Acyl-CoA dehydrogenase tetramer
• 
  Acyl-CoA dehydrogenase enzyme
• 
  Active site of Acyl-CoA dehydrogenase

Acyl-CoA Dehydrogenase

Acyl-CoA dehydrogenase is a family of enzymes that play a crucial role in the beta-oxidation of fatty acids in the mitochondria of eukaryotic cells. These enzymes catalyze the initial step in the breakdown of fatty acids, which is essential for the production of ATP, the energy currency of the cell.

Function

Acyl-CoA dehydrogenases are responsible for the dehydrogenation of acyl-CoA molecules, which are fatty acids bound to coenzyme A. This reaction involves the removal of two hydrogen atoms from the acyl-CoA, resulting in the formation of a trans double bond between the beta and alpha carbon atoms, producing a trans-2-enoyl-CoA. This step is the first in a series of reactions that ultimately lead to the complete oxidation of fatty acids into acetyl-CoA, which can then enter the citric acid cycle for further energy production.

Types

There are several types of acyl-CoA dehydrogenases, each specific to the chain length of the fatty acid substrate they act upon. These include:

• Short-chain acyl-CoA dehydrogenase (SCAD): Acts on fatty acids with chain lengths of 4-6 carbon atoms.
• Medium-chain acyl-CoA dehydrogenase (MCAD): Acts on fatty acids with chain lengths of 6-12 carbon atoms.
• Long-chain acyl-CoA dehydrogenase (LCAD): Acts on fatty acids with chain lengths of 12-18 carbon atoms.
• Very-long-chain acyl-CoA dehydrogenase (VLCAD): Acts on fatty acids with chain lengths greater than 18 carbon atoms.

Clinical Significance

Deficiencies in acyl-CoA dehydrogenases can lead to metabolic disorders. For example, medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is a genetic disorder that impairs the body's ability to break down medium-chain fatty acids, leading to the accumulation of fatty acids and their derivatives, which can cause serious health problems, especially during periods of fasting or illness.

Related Enzymes

Acyl-CoA dehydrogenases are part of a larger family of flavoproteins, which use flavin adenine dinucleotide (FAD) as a cofactor. They are related to other enzymes involved in fatty acid metabolism, such as enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, and beta-ketothiolase, which together complete the beta-oxidation cycle.

Related Pages

• Beta-oxidation
• Fatty acid metabolism
• Flavoprotein
• Medium-chain acyl-CoA dehydrogenase deficiency
• Mitochondria