Β-Hydroxy β-methylbutyryl-CoA

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.

β-Hydroxy β-methylbutyryl-CoA

Names
IUPAC name 3′-O-Phosphonoadenosine 5′-[(3R)-3-hydroxy-4-{[3-({2-[(3-hydroxy-3-methylbutanoyl)sulfanyl]ethyl}amino)-3-oxopropyl]amino}-2,2-dimethyl-4-oxobutyl dihydrogen diphosphate]
Systematic 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 β-hydroxyisovaleryl-CoA 3-hydroxyisovaleryl-CoA 3-hydroxy-3-methylbutyryl-CoA
Identifiers
3D model (JSmol)	Interactive image
ChEBI	CHEBI:28291
ChemSpider	10140181
KEGG	C05998
PubChem CID	11966188
CompTox Dashboard (EPA)	DTXSID001336036
InChI InChI=1S/C26H44N7O18P3S/c1-25(2,20(37)23(38)29-6-5-15(34)28-7-8-55-16(35)9-26(3,4)39)11-48-54(45,46)51-53(43,44)47-10-14-19(50-52(40,41)42)18(36)24(49-14)33-13-32-17-21(27)30-12-31-22(17)33/h12-14,18-20,24,36-37,39H,5-11H2,1-4H3,(H,28,34)(H,29,38)(H,43,44)(H,45,46)(H2,27,30,31)(H2,40,41,42)/t14-,18-,19-,20+,24-/m1/s1 Key: PEVZKILCBDEOBT-CITAKDKDSA-N
SMILES CC(C)(CC(=O)SCCNC(=O)CCNC(=O)[C@@H](C(C)(C)COP(=O)(O)OP(=O)(O)OC[C@@H]1[C@H]([C@H]([C@@H](O1)N2C=NC3=C(N=CN=C32)N)O)OP(=O)(O)O)O)O
Properties
Chemical formula	C26H44N7O18P3S
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

Metabolic pathway

Leucine metabolism in humans L-Leucine Branched-chain amino acid aminotransferase α-Ketoglutarate Glutamate Glutamate Alanine Pyruvate Muscle: α-Ketoisocaproate (α-KIC) Liver: α-Ketoisocaproate (α-KIC) Branched-chain α-ketoacid dehydrogenase (mitochondria) KIC-dioxygenase (cytosol) Isovaleryl-CoA β-Hydroxy β-methylbutyrate (HMB) Excreted in urine (10–40%) HMB-CoA β-Hydroxy β-methylglutaryl-CoA (HMG-CoA) β-Methylcrotonyl-CoA (MC-CoA) β-Methylglutaconyl-CoA (MG-CoA) CO2 CO2 O2 CO2 H2O CO2 H2O (liver) HMG-CoA lyase Enoyl-CoA hydratase Isovaleryl-CoA dehydrogenase MC-CoA carboxylase MG-CoA hydratase HMG-CoA reductase HMG-CoA  synthase β-Hydroxybutyrate dehydrogenase Mevalonate pathway Thiolase Unknown enzyme β-Hydroxybutyrate Acetoacetyl-CoA Acetyl-CoA Acetoacetate Mevalonate Cholesterol [note 1] Human metabolic pathway for HMB and isovaleryl-CoA relative to L-leucine.[1][5][2] Of the two major pathways, L-leucine is mostly metabolized into isovaleryl-CoA, while only about 5% is metabolized into HMB.[1][5][2]

Notes

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