Gamma-butyrobetaine dioxygenase

Gamma-butyrobetaine dioxygenase (GBBD) is an enzyme that plays a crucial role in the biosynthesis of L-carnitine, a compound essential for the transport of fatty acids into mitochondria for beta-oxidation. This enzyme catalyzes the final step in the L-carnitine biosynthetic pathway, converting gamma-butyrobetaine into L-carnitine. The activity of gamma-butyrobetaine dioxygenase is critical for energy metabolism, especially in tissues that rely heavily on fatty acids as an energy source, such as the heart and skeletal muscles.

Function

Gamma-butyrobetaine dioxygenase is involved in the metabolism of fatty acids, where it catalyzes the hydroxylation of gamma-butyrobetaine to form L-carnitine. L-carnitine is essential for the transport of long-chain fatty acids from the cytosol into the mitochondria, where they undergo beta-oxidation to produce energy. This process is vital for maintaining energy homeostasis in the body, particularly during periods of fasting or exercise.

Structure

The enzyme gamma-butyrobetaine dioxygenase is a monomeric protein that requires iron (Fe2+) and ascorbic acid (vitamin C) as cofactors for its catalytic activity. The structure of GBBD includes a catalytic domain that binds the substrate, gamma-butyrobetaine, and the cofactors, facilitating the hydroxylation reaction.

Genetics

The gene encoding gamma-butyrobetaine dioxygenase is located on the human chromosome 18. Mutations in this gene can affect the enzyme's activity, leading to reduced levels of L-carnitine and potentially resulting in metabolic disorders related to impaired fatty acid oxidation.

Clinical Significance

Deficiencies in gamma-butyrobetaine dioxygenase activity can lead to a decrease in L-carnitine levels, which may result in muscle weakness, fatigue, and metabolic disorders. Additionally, the enzyme has been studied for its role in cardiovascular diseases, as L-carnitine supplementation has been suggested to have beneficial effects on heart health.

See Also

• L-carnitine
• Beta-oxidation
• Metabolism
• Fatty acid metabolism

References

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