Chemistry:Beta-Hydroxy beta-methylbutyryl-CoA

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β-Hydroxy β-methylbutyryl-CoA
3-hydroxy-3-methylbutyryl coenzyme A.svg
Preferred IUPAC name
O1-{[(2R,3S,4R,5R)-5-(6-Amino-9H-purin-9-yl)-4-hydroxy-3-(phosphonooxy)oxolan-2-yl]methyl} O3-[(3R)-3-hydroxy-4-{[3-({2-[(3-hydroxy-3-methylbutanoyl)sulfanyl]ethyl}amino)-3-oxopropyl]amino}-2,2-dimethyl-4-oxobutyl] dihydrogen diphosphate
Other names
3D model (JSmol)
Molar mass 867.649946
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

β-Hydroxy β-methylbutyryl-coenzyme A (HMB-CoA), also known as 3-hydroxyisovaleryl-CoA, is a metabolite of L-leucine that is produced in the human body.[1][2] Its immediate precursors are β-hydroxy β-methylbutyric acid (HMB) and β-methylcrotonoyl-CoA (MC-CoA). It can be metabolized into HMB, MC-CoA, and HMG-CoA in humans.

Metabolic pathway


  1. This reaction is catalyzed by an unknown thioesterase enzyme.[3][4]


  1. 1.0 1.1 1.2 "International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB)". Journal of the International Society of Sports Nutrition 10 (1): 6. February 2013. doi:10.1186/1550-2783-10-6. PMID 23374455. 
  2. 2.0 2.1 2.2 Nutrient Metabolism: Structures, Functions, and Genes (2nd ed.). Academic Press. May 2015. pp. 385–388. ISBN 978-0-12-387784-0. Retrieved 6 June 2016. "Energy fuel: Eventually, most Leu is broken down, providing about 6.0kcal/g. About 60% of ingested Leu is oxidized within a few hours ... Ketogenesis: A significant proportion (40% of an ingested dose) is converted into acetyl-CoA and thereby contributes to the synthesis of ketones, steroids, fatty acids, and other compounds" 
    Figure 8.57: Metabolism of L-leucine
  3. "KEGG Reaction: R10759". Kanehisa Laboratories. Retrieved 24 June 2016. 
  4. "Urinary excretion of 3-hydroxyisovaleric acid and 3-hydroxyisovaleryl carnitine increases in response to a leucine challenge in marginally biotin-deficient humans". The Journal of Nutrition 141 (11): 1925–1930. November 2011. doi:10.3945/jn.111.146126. PMID 21918059. "Metabolic impairment diverts methylcrotonyl CoA to 3-hydroxyisovaleryl CoA in a reaction catalyzed by enoyl-CoA hydratase (22, 23). 3-Hydroxyisovaleryl CoA accumulation can inhibit cellular respiration either directly or via effects on the ratios of acyl CoA:free CoA if further metabolism and detoxification of 3-hydroxyisovaleryl CoA does not occur (22). The transfer to carnitine by 4 carnitine acyl-CoA transferases distributed in subcellular compartments likely serves as an important reservoir for acyl moieties (39–41). 3-Hydroxyisovaleryl CoA is likely detoxified by carnitine acetyltransferase producing 3HIA-carnitine, which is transported across the inner mitochondrial membrane (and hence effectively out of the mitochondria) via carnitine-acylcarnitine translocase (39). 3HIA-carnitine is thought to be either directly deacylated by a hydrolase to 3HIA or to undergo a second CoA exchange to again form 3-hydroxyisovaleryl CoA followed by release of 3HIA and free CoA by a thioesterase.".