ACAD9

ACAD9, also known as acyl-CoA dehydrogenase family member 9, is an enzyme encoded by the ACAD9 gene in humans. It belongs to the acyl-CoA dehydrogenase family, which plays a crucial role in the mitochondrial beta-oxidation pathway, responsible for the breakdown of fatty acids to produce energy. ACAD9 specifically functions as a mitochondrial flavoprotein that catalyzes the oxidation of long-chain acyl-CoA substrates.

The enzyme is notable for its dual role in metabolism and mitochondrial complex assembly. Aside from its dehydrogenase activity, ACAD9 is involved in the assembly of mitochondrial respiratory chain complex I, an essential component of the electron transport chain responsible for ATP production. Mutations in the ACAD9 gene have been associated with mitochondrial complex I deficiency, leading to a spectrum of clinical manifestations including Leigh syndrome, cardiomyopathy, and muscle weakness.

Structurally, ACAD9 shares conserved domains with other acyl-CoA dehydrogenases, with a characteristic FAD-binding site critical for its enzymatic activity. Its expression is primarily observed in tissues with high-energy demands such as cardiac and skeletal muscles.

Research into ACAD9 is ongoing, as understanding its functions can provide insights into mitochondrial disorders and potential therapeutic targets for related metabolic diseases. Due to its role in both fatty acid metabolism and mitochondrial function, ACAD9 is considered an important enzyme in cellular energy homeostasis.