Gamma-butyrobetaine dioxygenase (BBOX1 (gene symbol); BBOX, GBBH, or gamma-BBH are also used[3][4][2])

Gamma-butyrobetaine dioxygenase is an iron-dependent, 2-oxoglutarate-dependent enzyme that catalyzes the final step in the biosynthesis of L-carnitine from gamma-butyrobetaine. This reaction is crucial for the cellular uptake and mitochondrial transfer of long-chain fatty acids, thus playing an essential role in energy production, particularly in heart and muscle. The enzyme is widely expressed in human tissues—highly in the kidney, moderately in the liver, and minimally in the brain. The gene encoding this enzyme is BBOX1. It is targeted by the drug mildronate (meldonium), which inhibits its activity and is clinically used in some countries for cardiovascular conditions by shifting energy metabolism away from fatty acid oxidation toward increased glucose utilization. Dysfunction or inhibition of this enzyme can result in L-carnitine deficiency, affecting cardiac and skeletal muscle function[3][5][4][10][1].

Other names

Gamma-butyrobetaine hydroxylaseGamma-butyrobetaine,2-oxoglutarate dioxygenaseBBOXGBBHgamma-BBHBBOX1 (gene symbol)[3][4][2]

Enzyme inhibition (e.g., mildronate competitively and irreversibly inhibits formation of carnitine from gamma-butyrobetaine)[5] Cofactor dependency (ascorbic acid required for optimal function)[4]