WordNet

an amino acid that does not occur in proteins but is important in the formation of urea

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/30 15:43:41」(JST)

wiki en

Ornithine is an amino acid that plays a role in the urea cycle. Ornithine is abnormally accumulated in the body in ornithine transcarbamylase deficiency.

Role in urea cycle

L-Ornithine is one of the products of the action of the enzyme arginase on L-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 (phosphate-CONH₂). Ornithine is converted into a urea derivative at the δ (terminal) nitrogen by carbamoyl phosphate. Another nitrogen is added from aspartate, producing the denitrogenated fumarate, and the resulting arginine (a guanidinium compound) is hydrolysed back to ornithine, producing urea. The nitrogens of urea come from the ammonia and aspartate, and the nitrogen in ornithine remains intact.

Ornithine lactamization

Ornithine is not an amino acid coded for by DNA, that is, not 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.^[2]

Other reactions

Ornithine, via the action of ornithine decarboxylase (E.C. 4.1.1.17), is the starting point for the synthesis of polyamines such as putrescine.

In bacteria, such as E. coli, ornithine can be synthesized from L-glutamate.^[3]

Ornithine is also the starting point for cocaine biosynthesis, when decarboxylated, then modified greatly by cytochrome P450.

Potential medical uses

Exercise fatigue

L-Ornithine supplementation attenuated fatigue in subjects in a placebo-controlled study using a cycle ergometer. The results suggested that L-ornithine has an antifatigue effect in increasing the efficiency of energy consumption and promoting the excretion of ammonia.^[4]^[5]

Cirrhosis

L-Ornithine L-aspartate (LOLA), a stable salt of ornithine and aspartic acid, has been used in the treatment of cirrhosis.^[6]

Weightlifting supplement

Amino acid supplements, including L-ornithine, are frequently marketed to bodybuilders and weightlifters through the claim that it will increase levels of human growth hormone (HGH). However, clinical study has shown that these supplements do not increase levels of HGH with low dose (2 grams per day divided into two doses) supplementation.^[7]

Erectile Dysfunction

For erectile dysfunction it's recommended to be used in combination with L-Arginine.

References

^ Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. p. C-408. ISBN 0-8493-0462-8. .
^ Arthur L. Weber and Stanley L. Miller (1981). "Reasons for the Occurrence of the Twenty Coded Protein Amino Acids". J. Mol. Evol. 17 (5): 273–284. doi:10.1007/BF01795749. PMID 7277510.
^ Ornithine Biosynthesis. School of Biological and Chemical Sciences, Queen Mary, University of London. Retrieved 2007-08-17 .
^ Sugino, T; Shirai, T; Kajimoto, Y; Kajimoto, O (2008). "L-ornithine supplementation attenuates physical fatigue in healthy volunteers by modulating lipid and amino acid metabolism". Nutrition research 28 (11): 738–43. doi:10.1016/j.nutres.2008.08.008. PMID 19083482.
^ Demura, S; Yamada, T; Yamaji, S; Komatsu, M; Morishita, K (2010). "The effect of L-ornithine hydrochloride ingestion on performance during incremental exhaustive ergometer bicycle exercise and ammonia metabolism during and after exercise". European journal of clinical nutrition 64 (10): 1166–71. doi:10.1038/ejcn.2010.149. PMID 20717126.
^ Sikorska, H; Cianciara, J; Wiercińska-Drapało, A (2010). "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". Polski merkuriusz lekarski : organ Polskiego Towarzystwa Lekarskiego 28 (168): 490–5. PMID 20642112.
^ Fogelholm et al.; Näveri, HK; Kiilavuori, KT; Härkönen, MH (1993). "Low-dose amino acid supplementation: no effects on serum human growth hormone and insulin in male weightlifters". International Journal of Sport Nutrition 3 (3): 290–297. PMID 8220394.

External links

Ornithine MS Spectrum

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 成人における肝性脳症：治療 hepatic encephalopathy in adults treatment
2. 尿素サイクル障害：臨床的特徴および診断 urea cycle disorders clinical features and diagnosis
3. 尿素サイクル障害：管理 urea cycle disorders management
4. 重症患者における栄養補給：経腸栄養 nutrition support in critically ill patients enteral nutrition
5. 先天性代謝異常：個々の障害の発見 inborn errors of metabolism identifying the specific disorder

English Journal

Two continuous coupled assays for ornithine-δ-aminotransferase.

Juncosa JI, Lee H, Silverman RB.SourceDepartment of Chemistry, Chemistry of Life Processes Institute, and Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, IL 60208, USA.
Analytical biochemistry.Anal Biochem.2013 Sep 15;440(2):145-9. doi: 10.1016/j.ab.2013.05.025. Epub 2013 Jun 5.
We have developed two new continuous coupled assays for ornithine-δ-aminotransferase (OAT) that are more sensitive than previous methods, measure activity in real time, and can be carried out in multiwell plates for convenience and high throughput. The first assay is based on the reduction of Δ(1)
PMID 23747282

A case with combined rare inborn metabolic disorders: Congenital adrenal hyperplasia and ornithine transcarbamylase deficiency.

Kim YM, Lee BH, Choi JH, Kim GH, Lim HH, Yoo HW.SourceDepartment of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Gene.Gene.2013 Sep 15;527(1):394-6. doi: 10.1016/j.gene.2013.03.096. Epub 2013 Jun 12.
Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is a common autosomal recessive disorder. Ornithine transcarbamylase (OTC) deficiency is the most common urea cycle disorder and demonstrates X-linked inheritance. In female OTC deficiency, phenotypes are variable according to X-i
PMID 23769969

AMXT-1501, a novel polyamine transport inhibitor, synergizes with DFMO in inhibiting neuroblastoma cell proliferation by targeting both ornithine decarboxylase and polyamine transport.

Samal K, Zhao P, Kendzicky A, Yco LP, McClung H, Gerner E, Burns M, Bachmann AS, Sholler G.SourceCenter for Translational Medicine, Van Andel Research Institute, Grand Rapids, Michigan.
International journal of cancer. Journal international du cancer.Int J Cancer.2013 Sep 15;133(6):1323-33. doi: 10.1002/ijc.28139. Epub 2013 May 30.
Neuroblastoma (NB) is associated with MYCN oncogene amplification occurring in approximately 30% of NBs and is associated with poor prognosis. MYCN is linked to a number of genes including ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis. ODC expression is elevated i
PMID 23457004

Japanese Journal

Non-invasive measurement of skin autofluorescence to evaluate diabetic complications

Journal of Clinical Biochemistry and Nutrition 58(2), 135-140, 2016
NAID 130005132521

モモシュート組織におけるデハードニング時の温度上昇に応答したプロリン蓄積

The Horticulture Journal 85(1), 37-45, 2016
NAID 130005121325

Non-invasive measurement of skin autofluorescence to evaluate diabetic complications

Journal of Clinical Biochemistry and Nutrition advpub(0), 2016
NAID 130005120617

Related Pictures

★リンクテーブル★

リンク元	「オルニチン回路」「オルニチン」
拡張検索	「ornithine carbamoyl transferase」「ornithine-oxo-acid transaminase」「dibenzoylornithine」

「オルニチン回路」

L-Ornithine
	IUPAC name L-Ornithine
	Other names (+)-(S)-2,5-Diaminovaleric acid, (+)-(S)-2,5-Diaminopentanoic acid
Identifiers
CAS number	70-26-8
PubChem	389
ChemSpider	6026
UNII	E524N2IXA3
EC-number	200-731-7
DrugBank	DB00129
KEGG	D08302
MeSH	Ornithine
ChEBI	CHEBI:15729
ChEMBL	CHEMBL446143
Jmol-3D images	Image 1
	SMILES O=C(O)[C@@H](N)CCCN ;
	InChI InChI=1S/C5H12N2O2/c6-3-1-2-4(7)5(8)9/h4H,1-3,6-7H2,(H,8,9)/t4-/m0/s1 ; Key: AHLPHDHHMVZTML-BYPYZUCNSA-N InChI=1/C5H12N2O2/c6-3-1-2-4(7)5(8)9/h4H,1-3,6-7H2,(H,8,9)/t4-/m0/s1 InChI=1/C5H12N2O2/c6-3-1-2-4(7)5(8)9/h4H,1-3,6-7H2,(H,8,9)/t4-/m0/s1; Key: AHLPHDHHMVZTML-BYPYZUCNBZ ;
Properties
Molecular formula	C5H12N2O2
Molar mass	132.16 g/mol
Melting point	140 °C (284 °F; 413 K)
Solubility in water	soluble
Solubility	soluble in ethanol
Acidity (pKa)	1.94
Chiral rotation [α]D	+11.5 (H2O, c = 6.5)
	Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
	(verify) (what is: /?)
	Infobox references

　　[★]

英: ornithine cycle
同: 尿素サイクル尿素回路 urea cycle、クレブス-ヘンゼライト回路 Krebs-Henseleit cycle、オルニチンサイクル
関: オルニチン、尿素

オルニチン回路に含まれる分子はアミノ酸である：アミノ基とカルボン酸を両方持つもの
最終産物である尿素の窒素は、アンモニアとアスパラギン酸に由来する

ミトコンドリア内の反応

1) アンモニア + 炭酸 + 2ATP → ADP + Pi + カルバモイルリン酸 
　　　　　　　　　　　　5)から
　　　　　　　　　　　　↓
2) カルバモイルリン酸 + オルニチン → シトルリン + Pi 
　　　　　　　　　　　　　　　　　　　↓
　　　　　　　　　　　　　　　　　　　3)へ

サイトソルの反応

　　2)から
　　↓
3) シトルリン + アスパラギン酸 + ATP → AMP + ピロリン酸 + アルギニノコハク酸 
4) アルギニノコハク酸 → フマル酸 + アルギニン 
5) アルギニン + 水 → 尿素 + オルニチン 
　　　　　　　　　　　　　　　↓
　　　　　　　　　　　　　　　2)へ

|
ornithine
|
----------mitochondria
|
ornithine
|
|<-carbamoyl phosphate {ornithine transcarbamoylase}
|
citrulline
|
----------mitochondria
|
citrulline
|
|<-aspartate {argininosuccinate synthase}
|
argininosuccinate
| 
|->fumarate {argininosuccinase}
|
arginine
|
|<-H2O
|           {arginase}
|->urea
|
ornithine
|

臨床関連

尿素サイクル異常症

「オルニチン」

　　[★]

英: ornithine, Orn
同: α,δ-ジアミノ-n-吉草酸 α,δ-diamino-n-valeric acid、2,5-ジアミノ-n-吉草酸 2,5-diamino-n-valeric acid、2,5ジアミノペンタン酸 2,5-diamino pentanoic acid
関: オルニチン回路

アミノ酸の一種
尿素回路でアルギニンから得られる。アルギニンから-C(NH)(NH₃⁺)が取れた形。
極性、塩基性

　-CH2-CH2-CH2-NH2
  α  β  γ ＞γアミノ基を有する。即ち、側鎖には炭素が３つ含まれる。＜リジンと比べて炭素が一つ少ない。