Category: biosynthesis
CoA (coenzyme A) is the central acyl-carrier in metabolism — present in acetyl-CoA, succinyl-CoA, fatty acyl-CoA, HMG-CoA, every acyl-CoA species. Biosynthesized from pantothenate (vitamin B5) via five enzymatic steps: pantothenate → 4'-phosphopantothenate (PANK1-4, RATE-LIMITING) → 4'-phospho-N-pantothenoylcysteine → 4'-phosphopantetheine → dephospho-CoA → CoA. PANK2 deficiency causes PKAN (pantothenate kinase-associated neurodegeneration, formerly Hallervorden-Spatz) — autosomal recessive with iron accumulation in basal ganglia ("eye-of-the-tiger" MRI sign); experimental treatment with deferiprone + fosmetpantotenate. Holo-acyl carrier protein (ACP, fatty acid synthase component) also uses the phosphopantetheine arm.