Ornithine: Difference between revisions

|Verifiedfields = changed

|Watchedfields = changed

|verifiedrevid = 408781245

|Name = {{sm|l}}-Ornithine

|ImageFile = L-Ornithin2.svg

|ImageFile1 = Ornithine ball-and-stick.png

|IUPACName = <small>L</small>-Ornithine

|OtherNames = (+)-(''S'')-2,5-Diaminovaleric acid <br />(+)-(''S'')-2,5-Diaminopentanoic acid

|Section1={{Chembox Identifiers

|IUPHAR_ligand = 725

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = E524N2IXA3

|InChI=1/C5H12N2O2/c6-3-1-2-4(7)5(8)9/h4H,1-3,6-7H2,(H,8,9)/t4-/m0/s1

|InChI1 = 1/C5H12N2O2/c6-3-1-2-4(7)5(8)9/h4H,1-3,6-7H2,(H,8,9)/t4-/m0/s1

|InChIKey1 = AHLPHDHHMVZTML-BYPYZUCNBZ

|ChEMBL_Ref = {{ebicite|correct|EBI}}

|ChEMBL = 446143

|StdInChI_Ref = {{stdinchicite|correct|chemspider}}

|StdInChI = 1S/C5H12N2O2/c6-3-1-2-4(7)5(8)9/h4H,1-3,6-7H2,(H,8,9)/t4-/m0/s1

|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

|StdInChIKey = AHLPHDHHMVZTML-BYPYZUCNSA-N

|CASNo = 70-26-8

|CASNo_Ref = {{cascite|correct|CAS}}

|EC_number = 200-731-7

|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

|ChemSpiderID = 6026

|PubChem = 389

|KEGG_Ref = {{keggcite|correct|kegg}}

|KEGG = D08302

|DrugBank_Ref = {{drugbankcite|changed|drugbank}}

|DrugBank = DB00129

|ChEBI_Ref = {{ebicite|changed|EBI}}

|ChEBI = 15729

|SMILES = O=C(O)[C@@H](N)CCCN

|MeSHName = Ornithine

|Section2={{Chembox Properties

|Properties_ref = <ref>{{RubberBible62nd|page=C-408}}</ref>

|Formula = C₅H₁₂N₂O₂

|MolarMass = 132.16 g/mol

|MeltingPtC = 140

|Solubility = soluble

|SolubleOther = soluble in [[ethanol]]

|SpecRotation = +11.5 (H₂O, ''c'' = 6.5)

|pKa = 1.94

}}

}}

'''Ornithine''' is a [[non-proteinogenic]] α-amino acid that plays a role in the [[urea cycle]]. Ornithine is abnormally accumulated in the body in [[ornithine transcarbamylase deficiency]]. The [[Moiety (chemistry)|radical]] is '''ornithyl'''.<ref name="pmid27978498">{{cite journal |vauthors=Sivashanmugam M |title=Ornithine and its role in metabolic diseases: An appraisal |journal=Biomed Pharmacother |volume=86 |issue= |pages=185–194 |date=February 2017 |pmid=27978498 |doi=10.1016/j.biopha.2016.12.024 |url=}}</ref>

<small>L</small>-Ornithine is one of the products of the action of the enzyme [[arginase]] on <small>L</small>-[[arginine]], creating [[urea]]. Therefore, ornithine is a central part of the urea cycle, which allows for the disposal of excess [[nitrogen]]. Ornithine is recycled and, in a manner, is a catalyst. First, ammonia is converted into [[carbamoyl phosphate]] ({{chem|H|2|NC(O)OPO|3|2−}}) by carbamoyl phosphate synthetase. [[Ornithine transcarbamylase]] catalyzes the reaction between carbamoyl phosphate and ornithine to form [[citrulline]] and phosphate (P_i). Another [[amino group]] is added from [[aspartate]], producing [[arginine]] and denitrogenated [[fumarate]]. The resulting [[arginine]] (a [[guanidinium]] compound) is hydrolysed back to ornithine, producing urea. The amino groups of urea come from the ammonia and aspartate, and the nitrogen in ornithine remains intact.

[[Image:OTC reaction.png|thumb|left|458px|'''Reaction mechanism:'''. The [[Side chain|side-chain]] amino group of ornithine (Orn) attacks the carbonyl carbon of carbamoyl phosphate (CP) nucleophilically, ''left'', to form a tetrahedral transition state, ''middle''. Charge rearrangement releases citrulline (Cit) and phosphate (P_i), ''right''.<ref name="pmid10747936">{{cite journal | vauthors = Langley DB, Templeton MD, Fields BA, Mitchell RE, Collyer CA | title = Mechanism of inactivation of ornithine transcarbamoylase by Ndelta -(N'-Sulfodiaminophosphinyl)-L-ornithine, a true transition state analogue? Crystal structure and implications for catalytic mechanism | journal = The Journal of Biological Chemistry | volume = 275 | issue = 26 | pages = 20012–9 | date = June 2000 | pmid = 10747936 | doi = 10.1074/jbc.M000585200 | doi-access = free }}</ref> ]]{{clear|left}}

Ornithine is not an amino acid coded for by [[DNA]], that is, not [[Proteinogenic amino acid|proteinogenic]]. However, in mammalian non-hepatic tissues, the main use of the urea cycle is in arginine biosynthesis, so, as an intermediate in metabolic processes, ornithine is quite important.<ref>{{cite journal | vauthors = Weber AL, Miller SL | title = Reasons for the occurrence of the twenty coded protein amino acids | journal = Journal of Molecular Evolution | volume = 17 | issue = 5 | pages = 273–84 | year = 1981 | pmid = 7277510 | doi = 10.1007/BF01795749 | bibcode = 1981JMolE..17..273W | s2cid = 27957755 | url = http://physwww.mcmaster.ca/~higgsp/3D03/WeberReasons.pdf }}</ref>

{{clear|left}}

In bacteria, such as ''[[Escherichia coli|E. coli]]'', ornithine can be synthesized from [[glutamic acid|<small>L</small>-glutamate]].<ref>{{Cite journal | url = http://www.chem.qmul.ac.uk/iubmb/enzyme/reaction/AminoAcid/Orn.html | title = Ornithine Biosynthesis | access-date = 2007-08-17 | publisher = School of Biological and Chemical Sciences, Queen Mary, University of London | archive-url = https://web.archive.org/web/20120414191013/http://www.chem.qmul.ac.uk/iubmb/enzyme/reaction/AminoAcid/Orn.html | archive-date = 2012-04-14 | url-status = dead }}</ref>

[[File:Ornithine lactamization.svg|center|thumb|600px|Ornithine lactamization]]

==Research==

===Exercise fatigue===

<small>L</small>-Ornithine supplementation attenuated fatigue in subjects in a placebo-controlled study using a cycle ergometer. The results suggested that <small>L</small>-ornithine has an antifatigue effect in increasing the efficiency of energy consumption and promoting the excretion of ammonia.<ref>{{cite journal | vauthors = Sugino T, Shirai T, Kajimoto Y, Kajimoto O | title = L-ornithine supplementation attenuates physical fatigue in healthy volunteers by modulating lipid and amino acid metabolism | journal = Nutrition Research | volume = 28 | issue = 11 | pages = 738–43 | date = November 2008 | pmid = 19083482 | doi = 10.1016/j.nutres.2008.08.008 }}</ref><ref>{{cite journal | vauthors = Demura S, Yamada T, Yamaji S, Komatsu M, Morishita K | title = The effect of L-ornithine hydrochloride ingestion on performance during incremental exhaustive ergometer bicycle exercise and ammonia metabolism during and after exercise | journal = European Journal of Clinical Nutrition | volume = 64 | issue = 10 | pages = 1166–71 | date = October 2010 | pmid = 20717126 | doi = 10.1038/ejcn.2010.149 | doi-access = free | hdl = 2297/25434 | hdl-access = free }}</ref>

===Weightlifting supplement===

[[Amino acid]] supplements, including <small>L</small>-ornithine, are frequently marketed to bodybuilders and weightlifters with claims for increasing levels of [[human growth hormone]] (HGH), muscle mass, and strength. A 1993 short 4-day clinical study reported that <small>L</small>-ornithine in combination with <small>L</small>-arginine and <small>L</small>-lysine at 2 g/d each did not increase HGH.<ref>{{cite journal | vauthors = Fogelholm GM, Näveri HK, Kiilavuori KT, Härkönen MH | title = Low-dose amino acid supplementation: no effects on serum human growth hormone and insulin in male weightlifters | journal = International Journal of Sport Nutrition | volume = 3 | issue = 3 | pages = 290–7 | date = September 1993 | pmid = 8220394 | doi = 10.1123/ijsn.3.3.290 }}</ref> A review from 2002 on the topic concluded "The use of specific amino acids to stimulate GH release by athletes is not recommended."<ref>{{cite journal | vauthors = Chromiak JA, Antonio J | title = Use of amino acids as growth hormone-releasing agents by athletes | journal = Nutrition | volume = 18 | issue = 7–8 | pages = 657–61 | year = 2002 | pmid = 12093449 | doi = 10.1016/s0899-9007(02)00807-9 }}</ref>

===Cirrhosis===

[[Hepatic_encephalopathy#L-ornithine_and_L-aspartate|<small>L</small>-Ornithine <small>L</small>-aspartate]] (LOLA), a stable salt of ornithine and aspartic acid, has been used in the treatment of [[cirrhosis]]<ref>{{cite journal | vauthors = Sikorska H, Cianciara J, Wiercińska-Drapało A | title = [Physiological functions of L-ornithine and L-aspartate in the body and the efficacy of administration of L-ornithine-L-aspartate in conditions of relative deficiency] | journal = Polski Merkuriusz Lekarski | volume = 28 | issue = 168 | pages = 490–5 | date = June 2010 | pmid = 20642112 | url = https://www.researchgate.net/publication/45273344 }}</ref> and hepatic encephalopathy.<ref name="pmid30706425">{{cite journal |vauthors=Butterworth R, Mcphail M |title=L-Ornithine L-Aspartate (LOLA) for Hepatic Encephalopathy in Cirrhosis: Results of Randomized Controlled Trials and Meta-Analyses |journal=Drugs |volume=79 |issue=Suppl 1 |pages=31–37 |date=February 2019 |pmid=30706425 |pmc=6416237 |doi=10.1007/s40265-018-1024-1 |url=}}</ref>

==See also==

* [[Bisorcic]]

== References ==

== External links ==

{{Commons category|L-Ornithine}}

* [http://gmd.mpimp-golm.mpg.de/Spectrums/13d582bc-51b1-4b92-8edf-cb1e31ca64c6.aspx Ornithine mass Spectrum]

{{Non-proteinogenic amino acids}}

[[Category:Alpha-Amino acids]]

[[Category:Urea cycle]]

[[Category:Diamines]]

[[Category:Non-proteinogenic amino acids]]