HMG-CoA

HMG-CoA
Names

IUPAC name (9R,21S)-1-[(2R,3S,4R,5R)-5-(6-amino-9H-purin-9-yl)-4-hydroxy-3-(phosphonooxy)tetrahydrofuran-2-yl]-3,5,9,21-tetrahydroxy-8,8,21-trimethyl-10,14,19-trioxo-2,4,6-trioxa-18-thia-11,15-diaza-3,5-diphosphatricosan-23-oic acid 3,5-dioxide
Other names 3-hydroxy-3-methylglutaryl CoA; 3-hydroxy-3-methylglutaryl coenzyme A
Identifiers
CAS Number	1553-55-5^Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:61659^Y
ChemSpider	392859^Y
ECHA InfoCard	100.014.820
IUPHAR/BPS	3040
MeSH	HMG-CoA
PubChem CID	445127
CompTox Dashboard (EPA)	DTXSID00935181
InChI InChI=1S/C27H44N7O20P3S/c1-26(2,21(40)24(41)30-5-4-15(35)29-6-7-58-17(38)9-27(3,42)8-16(36)37)11-51-57(48,49)54-56(46,47)50-10-14-20(53-55(43,44)45)19(39)25(52-14)34-13-33-18-22(28)31-12-32-23(18)34/h12-14,19-21,25,39-40,42H,4-11H2,1-3H3,(H,29,35)(H,30,41)(H,36,37)(H,46,47)(H,48,49)(H2,28,31,32)(H2,43,44,45)/t14-,19-,20-,21+,25-,27+/m1/s1^Y Key: CABVTRNMFUVUDM-VRHQGPGLSA-N^Y InChI=1/C27H44N7O20P3S/c1-26(2,21(40)24(41)30-5-4-15(35)29-6-7-58-17(38)9-27(3,42)8-16(36)37)11-51-57(48,49)54-56(46,47)50-10-14-20(53-55(43,44)45)19(39)25(52-14)34-13-33-18-22(28)31-12-32-23(18)34/h12-14,19-21,25,39-40,42H,4-11H2,1-3H3,(H,29,35)(H,30,41)(H,36,37)(H,46,47)(H,48,49)(H2,28,31,32)(H2,43,44,45)/t14-,19-,20-,21+,25-,27+/m1/s1 Key: CABVTRNMFUVUDM-VRHQGPGLBX
SMILES O=C(O)C[C@@](O)(C)CC(=O)SCCNC(=O)CCNC(=O)[C@H](O)C(C)(C)COP(=O)(O)OP(=O)(O)OC[C@H]3O[C@@H](n2cnc1c(ncnc12)N)[C@H](O)[C@@H]3OP(=O)(O)O
Properties
Chemical formula	C₂₇H₄₄N₇O₂₀P₃S
Molar mass	911.661 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is ^YN ?) Infobox references

β-Hydroxy β-methylglutaryl-CoA (HMG-CoA), also known as 3-hydroxy-3-methylglutaryl coenzyme A, is an intermediate in the mevalonate and ketogenesis pathways. It is formed from acetyl CoA and acetoacetyl CoA by HMG-CoA synthase. The research of Minor J. Coon and Bimal Kumar Bachhawat in the 1950s at University of Illinois led to its discovery.^[1]^[2]

HMG-CoA is a metabolic intermediate in the metabolism of the branched-chain amino acids, which include leucine, isoleucine, and valine.^[3] Its immediate precursors are β-methylglutaconyl-CoA (MG-CoA) and β-hydroxy β-methylbutyryl-CoA (HMB-CoA).^[4]^[5]^[6]

HMG-CoA reductase catalyzes the conversion of HMG-CoA to mevalonic acid, a necessary step in the biosynthesis of cholesterol.

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Transcription

Biosynthesis

Leucine metabolism in humans

L-Leucine

Branched-chain amino
acid aminotransferase

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

O₂

CO₂

H₂O

CO₂

H₂O

(liver)
HMG-CoA
lyase

Enoyl-CoA hydratase

Isovaleryl-CoA
dehydrogenase

β-Hydroxybutyrate
dehydrogenase

Unknown
enzyme

Human metabolic pathway for HMB and isovaleryl-CoA relative to L-leucine.^[4]^[7]^[6] Of the two major pathways, L-leucine is mostly metabolized into isovaleryl-CoA, while only about 5% is metabolized into HMB.^[4]^[7]^[6]

Mevalonate pathway

Mevalonate synthesis begins with the beta-ketothiolase-catalyzed Claisen condensation of two molecules of acetyl-CoA to produce acetoacetyl CoA. The following reaction involves the joining of acetyl-CoA and acetoacetyl-CoA to form HMG-CoA, a process catalyzed by HMG-CoA synthase.^[8]

In the final step of mevalonate biosynthesis, HMG-CoA reductase, an NADPH-dependent oxidoreductase, catalyzes the conversion of HMG-CoA into mevalonate, which is the primary regulatory point in this pathway. Mevalonate serves as the precursor to isoprenoid groups that are incorporated into a wide variety of end-products, including cholesterol in humans.^[9]

Ketogenesis pathway

HMG-CoA lyase breaks it into acetyl CoA and acetoacetate.

References

^ Sarkar DP (2015). "Classics in Indian Medicine" (PDF). The National Medical Journal of India (28): 3. Archived from the original (PDF) on 2016-05-31.
^ Surolia A (1997). "An outstanding scientist and a splendid human being". Glycobiology. 7 (4): v–ix. doi:10.1093/glycob/7.4.453.
^ "Valine, leucine and isoleucine degradation - Reference pathway". Kyoto Encyclopedia of Genes and Genomes. Kanehisa Laboratories. 27 January 2016. Retrieved 1 February 2018.
^ ^a ^b ^c Wilson JM, Fitschen PJ, Campbell B, Wilson GJ, Zanchi N, Taylor L, Wilborn C, Kalman DS, Stout JR, Hoffman JR, Ziegenfuss TN, Lopez HL, Kreider RB, Smith-Ryan AE, Antonio J (February 2013). "International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB)". Journal of the International Society of Sports Nutrition. 10 (1): 6. doi:10.1186/1550-2783-10-6. PMC 3568064. PMID 23374455.
^ Zanchi NE, Gerlinger-Romero F, Guimarães-Ferreira L, de Siqueira Filho MA, Felitti V, Lira FS, Seelaender M, Lancha AH (April 2011). "HMB supplementation: clinical and athletic performance-related effects and mechanisms of action". Amino Acids. 40 (4): 1015–1025. doi:10.1007/s00726-010-0678-0. PMID 20607321. S2CID 11120110. HMB is a metabolite of the amino acid leucine (Van Koverin and Nissen 1992), an essential amino acid. The first step in HMB metabolism is the reversible transamination of leucine to [α-KIC] that occurs mainly extrahepatically (Block and Buse 1990). Following this enzymatic reaction, [α-KIC] may follow one of two pathways. In the first, HMB is produced from [α-KIC] by the cytosolic enzyme KIC dioxygenase (Sabourin and Bieber 1983). The cytosolic dioxygenase has been characterized extensively and differs from the mitochondrial form in that the dioxygenase enzyme is a cytosolic enzyme, whereas the dehydrogenase enzyme is found exclusively in the mitochondrion (Sabourin and Bieber 1981, 1983). Importantly, this route of HMB formation is direct and completely dependent of liver KIC dioxygenase. Following this pathway, HMB in the cytosol is first converted to cytosolic β-hydroxy-β-methylglutaryl-CoA (HMG-CoA), which can then be directed for cholesterol synthesis (Rudney 1957) (Fig. 1). In fact, numerous biochemical studies have shown that HMB is a precursor of cholesterol (Zabin and Bloch 1951; Nissen et al. 2000).
^ ^a ^b ^c Kohlmeier M (May 2015). "Leucine". Nutrient Metabolism: Structures, Functions, and Genes (2nd ed.). Academic Press. 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
^ ^a ^b Zanchi NE, Gerlinger-Romero F, Guimarães-Ferreira L, de Siqueira Filho MA, Felitti V, Lira FS, Seelaender M, Lancha AH (April 2011). "HMB supplementation: clinical and athletic performance-related effects and mechanisms of action". Amino Acids. 40 (4): 1015–1025. doi:10.1007/s00726-010-0678-0. PMID 20607321. S2CID 11120110. HMB is a metabolite of the amino acid leucine (Van Koverin and Nissen 1992), an essential amino acid. The first step in HMB metabolism is the reversible transamination of leucine to [α-KIC] that occurs mainly extrahepatically (Block and Buse 1990). Following this enzymatic reaction, [α-KIC] may follow one of two pathways. In the first, HMB is produced from [α-KIC] by the cytosolic enzyme KIC dioxygenase (Sabourin and Bieber 1983). The cytosolic dioxygenase has been characterized extensively and differs from the mitochondrial form in that the dioxygenase enzyme is a cytosolic enzyme, whereas the dehydrogenase enzyme is found exclusively in the mitochondrion (Sabourin and Bieber 1981, 1983). Importantly, this route of HMB formation is direct and completely dependent of liver KIC dioxygenase. Following this pathway, HMB in the cytosol is first converted to cytosolic β-hydroxy-β-methylglutaryl-CoA (HMG-CoA), which can then be directed for cholesterol synthesis (Rudney 1957) (Fig. 1). In fact, numerous biochemical studies have shown that HMB is a precursor of cholesterol (Zabin and Bloch 1951; Nissen et al. 2000).
^ Garrett RH (2013). Biochemistry. Cengage Learning. p. 856. ISBN 978-1-305-57720-6.
^ Haines BE, Steussy CN, Stauffacher CV, Wiest O (October 2012). "Molecular modeling of the reaction pathway and hydride transfer reactions of HMG-CoA reductase". Biochemistry. 51 (40): 7983–95. doi:10.1021/bi3008593. PMC 3522576. PMID 22971202.

Cholesterol and steroid metabolic intermediates

Mevalonate pathway

to HMG-CoA	Acetyl-CoA Acetoacetyl-CoA HMB HMB-CoA HMG-CoA
Ketone bodies	Acetone Acetoacetic acid β-Hydroxybutyric acid
to DMAPP	Mevalonic acid Phosphomevalonic acid 5-Diphosphomevalonic acid Isopentenyl pyrophosphate Dimethylallyl pyrophosphate
Geranyl-	Geranyl pyrophosphate Geranylgeranyl pyrophosphate
Carotenoid	Prephytoene diphosphate Phytoene

Non-mevalonate pathway

To Cholesterol

Lanosterol
14-demethyllanosterol
4alpha-Methylzymosterol
Zymosterone
Zymosterol

From Cholesterol
to Steroid hormones

Nonhuman

To Sitosterol	Cycloartenol Cycloeucalenol Obtusifoliol 4α-methylfecosterol Isofucosterol 24-Methylenelophenol Sitosterol More Phytosterols see here instead.
To Ergocalciferol	Fecosterol Episterol Ergostatrienol Ergostatetraenol Ergosterol Ergocalciferol

Amino acid metabolism metabolic intermediates

K→acetyl-CoA

lysine→	Saccharopine Allysine α-Aminoadipic acid 2-Oxoadipic acid Glutaryl-CoA Glutaconyl-CoA Crotonyl-CoA β-Hydroxybutyryl-CoA
leucine→	β-Hydroxy β-methylbutyric acid β-Hydroxy β-methylbutyryl-CoA Isovaleryl-CoA α-Ketoisocaproic acid β-Ketoisocaproic acid β-Ketoisocaproyl-CoA β-Leucine β-Methylcrotonyl-CoA β-Methylglutaconyl-CoA β-Hydroxy β-methylglutaryl-CoA
tryptophan→alanine→	N′-Formylkynurenine Kynurenine Anthranilic acid 3-Hydroxykynurenine 3-Hydroxyanthranilic acid 2-Amino-3-carboxymuconic semialdehyde 2-Aminomuconic semialdehyde 2-Aminomuconic acid Glutaryl-CoA

G→pyruvate→
citrate

glycine→ serine→	3-Phosphoglyceric acid glycine→creatine: Glycocyamine Phosphocreatine Creatinine

G→glutamate→
α-ketoglutarate

histidine→	Urocanic acid Imidazol-4-one-5-propionic acid Formiminoglutamic acid Glutamate-1-semialdehyde
proline→	1-Pyrroline-5-carboxylic acid
arginine→	Agmatine Ornithine Citrulline Cadaverine Putrescine
other	cysteine+glutamate→glutathione: γ-Glutamylcysteine

G→propionyl-CoA→
succinyl-CoA

valine→	α-Ketoisovaleric acid Isobutyryl-CoA Methacrylyl-CoA 3-Hydroxyisobutyryl-CoA 3-Hydroxyisobutyric acid 2-Methyl-3-oxopropanoic acid
isoleucine→	2,3-Dihydroxy-3-methylpentanoic acid 2-Methylbutyryl-CoA Tiglyl-CoA 2-Methylacetoacetyl-CoA
methionine→	generation of homocysteine: S-Adenosyl methionine S-Adenosyl-L-homocysteine Homocysteine conversion to cysteine: Cystathionine α-Ketobutyric acid + Cysteine
threonine→	α-Ketobutyric acid
propionyl-CoA→	Methylmalonyl-CoA