^ abcWilson 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. PMC3568064. PMID 23374455.
^ abcKohlmeier M (May 2015). "Leucine". Nutrient Metabolism: Structures, Functions, and Genes (2nd ed.). Academic Press. pp. 385–388. ISBN978-0-12-387784-0. 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
^"KEGG Reaction: R10759". Kyoto Encyclopedia of Genes and Genomes. Kanehisa Laboratories. Retrieved 24 June 2016.
^Mock DM, Stratton SL, Horvath TD, Bogusiewicz A, Matthews NI, Henrich CL, Dawson AM, Spencer HJ, Owen SN, Boysen G, Moran JH (November 2011). "Urinary excretion of 3-hydroxyisovaleric acid and 3-hydroxyisovaleryl carnitine increases in response to a leucine challenge in marginally biotin-deficient humans". primary source. The Journal of Nutrition. 141 (11): 1925–1930. doi:10.3945/jn.111.146126. PMC3192457. 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.
^ abZanchi 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).
This biochemistry article is a stub. You can help Wikipedia by expanding it.
beta, hydroxy, beta, methylbutyryl, hydroxy, methylbutyryl, coenzyme, also, known, hydroxyisovaleryl, metabolite, leucine, that, produced, human, body, immediate, precursors, hydroxy, methylbutyric, acid, methylcrotonoyl, metabolized, into, humans, hydroxy, me. b Hydroxy b 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 b hydroxy b methylbutyric acid HMB and b methylcrotonoyl CoA MC CoA It can be metabolized into HMB MC CoA and HMG CoA in humans b Hydroxy b methylbutyryl CoA NamesIUPAC 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 diphosphateOther names b hydroxyisovaleryl CoA3 hydroxyisovaleryl CoA3 hydroxy 3 methylbutyryl CoAIdentifiers3D model JSmol Interactive imageChEBI CHEBI 28291ChemSpider 10140181KEGG C05998PubChem CID 11966188InChI 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 s1Key PEVZKILCBDEOBT CITAKDKDSA NSMILES 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 OPropertiesChemical formula C 26H 44N 7O 18P 3SMolar mass 867 649946Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Infobox referencesMetabolic pathway EditLeucine metabolism in humans nbsp L Leucine Branched chain aminoacid aminotransferase a Ketoglutarate Glutamate Glutamate Alanine Pyruvate Muscle a Ketoisocaproate a KIC Liver a Ketoisocaproate a KIC Branched chain a ketoaciddehydrogenase mitochondria KIC dioxygenase cytosol Isovaleryl CoA b Hydroxyb methylbutyrate HMB Excretedin urine 10 40 HMB CoA b Hydroxy b methylglutaryl CoA HMG CoA b Methylcrotonyl CoA MC CoA b Methylglutaconyl CoA MG CoA CO2 CO2 O2 CO2 H2O CO2 H2O liver HMG CoAlyase Enoyl CoA hydratase Isovaleryl CoAdehydrogenase MC CoAcarboxylase MG CoAhydratase HMG CoAreductase HMG CoA synthase b Hydroxybutyratedehydrogenase Mevalonatepathway Thiolase Unknownenzyme b Hydroxybutyrate Acetoacetyl CoA Acetyl CoA Acetoacetate Mevalonate Cholesterol note 1 nbsp 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 Edit This reaction is catalyzed by an unknown thioesterase enzyme 3 4 References Edit 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 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 KEGG Reaction R10759 Kyoto Encyclopedia of Genes and Genomes Kanehisa Laboratories Retrieved 24 June 2016 Mock DM Stratton SL Horvath TD Bogusiewicz A Matthews NI Henrich CL Dawson AM Spencer HJ Owen SN Boysen G Moran JH November 2011 Urinary excretion of 3 hydroxyisovaleric acid and 3 hydroxyisovaleryl carnitine increases in response to a leucine challenge in marginally biotin deficient humans primary source The Journal of Nutrition 141 11 1925 1930 doi 10 3945 jn 111 146126 PMC 3192457 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 a b Zanchi NE Gerlinger Romero F Guimaraes 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 a KIC that occurs mainly extrahepatically Block and Buse 1990 Following this enzymatic reaction a KIC may follow one of two pathways In the first HMB is produced from a 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 b hydroxy b 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 nbsp This biochemistry article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Beta Hydroxy beta methylbutyryl CoA amp oldid 1152365050, wikipedia, wiki, book, books, library,
