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Skeletal formula of arginine
Other names
2-Amino-5-guanidinopentanoic acid
3D model (JSmol)
3DMet B01331
1725411, 1725412 R, 1725413 S
ECHA InfoCard 100.000.738
EC Number 230-571-3
364938 R
MeSH Arginine
RTECS number CF1934200 S
Molar mass 174.20 g·mol−1
Appearance White crystals
Odor Odourless
Melting point 260 °C; 500 °F; 533 K
Boiling point 368 °C (694 °F; 641 K)
14.87 g/100 mL (20 °C)
Solubility slightly soluble in ethanol
insoluble in ethyl ether
log P −1.652
Acidity (pKa) 12.488
Basicity (pKb) 1.509
232.8 J K−1 mol−1 (at 23.7 °C)
250.6 J K−1 mol−1
−624.9–−622.3 kJ mol−1
−3.7396–−3.7370 MJ mol−1
B05XB01 (WHO) S
Safety data sheet See: data page
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word WARNING
Lethal dose or concentration (LD, LC):
5110 mg/kg (rat, oral)
Related compounds
Related alkanoic acids
Related compounds
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Phase behaviour
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Arginine (abbreviated as Arg or R) encoded by the codons CGU, CGC, CGA, CGG, AGA, and AGG[1] is an α-amino acid that is used in the biosynthesis of proteins.

Arginine is classified as a semiessential or conditionally essential amino acid, depending on the developmental stage and health status of the individual.[2] Preterm infants are unable to synthesize or create arginine internally, making the amino acid nutritionally essential for them.[3] Most healthy people do not need to supplement with arginine because it is a component of all protein-containing foods and their body produces sufficient amounts.[4]

Arginine was first isolated from a lupin seedling extract in 1886 by the German chemist Ernst Schultze.[5] It contains an α-amino group (which is in the protonated −NH3+ form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −COO form under biological conditions), and a side chain of a 3-carbon aliphatic straight chain capped by a complex guanidinium, classifying it as a charged (at physiological pH), aliphatic amino acid.


Dietary sources[edit]

A conditionally essential amino acid is one that may be required depending on the health status or life cycle of the individual. Arginine is one such conditionally essential amino acid. Endogenous synthesis may suffice, if not that, then synthesis plus absorption from protein-containing foods is enough. In rare instances a healthcare professional may recommend an arginine dietary supplement. Almost all dietary protein contains arginine (exception: gelatin):

  • Animal sources: Meat, fish, fowl, eggs, dairy
  • Plant sources: Grains, beans, corn, nuts; not fruits, vegetables or leafy greens


Arginine is synthesized from citrulline in arginine and proline metabolism by the sequential action of the cytosolic enzymes argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL). In terms of energy, this is costly, as the synthesis of each molecule of argininosuccinate requires hydrolysis of adenosine triphosphate (ATP) to adenosine monophosphate (AMP), i.e., two ATP equivalents. In essence, taking an excess of arginine gives more energy by saving ATPs that can be used elsewhere.

Citrulline can be derived from multiple sources:

The pathways linking arginine, glutamine, and proline are bidirectional. Thus, the net utilization or production of these amino acids is highly dependent on cell type and developmental stage.

On a whole-body basis, synthesis of arginine occurs principally via the intestinal–renal axis, wherein epithelial cells of the small intestine, which produce citrulline primarily from glutamine and glutamate, collaborate with the proximal tubule cells of the kidney, which extract citrulline from the circulation and convert it to arginine, which is returned to the circulation. As a consequence, impairment of small bowel or renal function can reduce endogenous arginine synthesis, thereby increasing the dietary requirement.

Synthesis of arginine from citrulline also occurs at a low level in many other cells, and cellular capacity for arginine synthesis can be markedly increased under circumstances that also induce iNOS. Thus, citrulline, a coproduct of the NOS-catalyzed reaction, can be recycled to arginine in a pathway known as the citrulline-NO or arginine-citrulline pathway. This is demonstrated by the fact that, in many cell types, citrulline can substitute for arginine to some degree in supporting NO synthesis. However, recycling is not quantitative because citrulline accumulates along with nitrate and nitrite, the stable end-products of NO, in NO-producing cells.[6]


Arginine plays an important role in cell division, the healing of wounds, removing ammonia from the body, immune function, and the release of hormones.[2][7][8]

The roles of endogenous arginine include:


The distributing basics of the moderate structure found in geometry, charge distribution, and ability to form multiple H-bonds make arginine ideal for binding negatively charged groups. For this reason, arginine prefers to be on the outside of the proteins, where it can interact with the polar environment.

Incorporated in proteins, arginine can also be converted to citrulline by PAD enzymes. In addition, arginine can be methylated by protein methyltransferases.


Arginine is the immediate precursor of nitric oxide (NO), urea, ornithine, and agmatine; is necessary for the synthesis of creatine; and can also be used for the synthesis of polyamines (mainly through ornithine and to a lesser degree through agmatine), citrulline, and glutamate. As a precursor of nitric oxide, arginine may have a role in the treatment of some conditions where vasodilation is required.[2] The presence of asymmetric dimethylarginine (ADMA), a close relative, inhibits the nitric oxide reaction; therefore, ADMA is considered a marker for vascular disease, just as L-arginine is considered a sign of a healthy endothelium.


L-arginine is generally recognized as safe (GRAS-status) at intakes of up to 20 grams per day.[15]


Delocalization of charge in guanidinium group of L-Arginine

The amino acid side-chain of arginine consists of a 3-carbon aliphatic straight chain, the distal end of which is capped by a complex guanidinium group.

With a pKa of 12.48, the guanidinium group will accept a positive charge in neutral, acidic, and even most basic environments, and thus imparts basic chemical properties to arginine. Because of the conjugation between the double bond and the nitrogen lone pairs, the positive charge is delocalized, enabling the formation of multiple H-bonds.


Growth hormone[edit]

Intravenously-administered arginine stimulates the secretion of growth hormone,[16] and for this reason is used in growth hormone stimulation tests.[17]

A review of clinical trials concluded that oral arginine increases growth hormone.[18] However, a more recent trial did not report an increase in growth hormone despite being effective at increasing plasma levels of L-arginine.[19]

MELAS syndrome[edit]

Several trials delved into effects of L-arginine in Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS syndrome), an inherited mitochondrial disease.[20]

High blood pressure[edit]

A meta-analysis showed that L-arginine reduces blood pressure with pooled estimates of 5.4/2.7 mmHg for SBP/DBP.[14]

Supplementation with L-arginine reduces diastolic blood pressure and lengthens pregnancy for women with gestational hypertension, including women with high blood pressure as part of pre-eclampsia. It did not lower systolic blood pressure or improve weight at birth.[21]

Hypersensitive teeth[edit]

A 2016 review of clinical trials of toothpastes marketed to help people with sensitive teeth and meta-analysis found that clinical trials were generally of poor quality, but based on the data at hand arginine-containing toothpastes appeared to be as effective in the long term as the other toothpastes tested.[22]

See also[edit]


  1. ^ IUPAC-IUBMB Joint Commission on Biochemical Nomenclature. "Nomenclature and Symbolism for Amino Acids and Peptides". Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc. Archived from the original on 29 May 2007. Retrieved 2007-05-17. 
  2. ^ a b c Tapiero H, Mathé G, Couvreur P, Tew KD (November 2002). "L-Arginine". (review). Biomedicine & Pharmacotherapy. 56 (9): 439–445. doi:10.1016/s0753-3322(02)00284-6. 
  3. ^ Wu G, Jaeger LA, Bazer FW, Rhoads JM (Aug 2004). "Arginine deficiency in preterm infants: biochemical mechanisms and nutritional implications". (review). The Journal of Nutritional Biochemistry. 15 (8): 442–51. PMID 15302078. doi:10.1016/j.jnutbio.2003.11.010. 
  4. ^ "Drugs and Supplements Arginine". Retrieved 15 January 2015. 
  5. ^ Saini, Rashmi; Badole, Sachin L.; Zanwar, Anand A. (2013). "Arginine Derived Nitric Oxide: Key to Healthy Skin". In Watson, Ronald Ross; Zibadi, Sherma. Bioactive Dietary Factors and Plant Extracts in Dermatology. Nutrition and Health. pp. 73–82. ISBN 978-1-62703-166-0. doi:10.1007/978-1-62703-167-7_8. 
  6. ^ Morris SM (Oct 2004). "Enzymes of arginine metabolism". (review). The Journal of Nutrition. 134 (10 Suppl): 2743S–2747S; discussion 2765S–2767S. PMID 15465778. 
  7. ^ a b Stechmiller JK, Childress B, Cowan L (Feb 2005). "Arginine supplementation and wound healing". (review). Nutrition in Clinical Practice. 20 (1): 52–61. PMID 16207646. doi:10.1177/011542650502000152. 
  8. ^ a b Witte MB, Barbul A (2003). "Arginine physiology and its implication for wound healing". (review). Wound Repair and Regeneration. 11 (6): 419–23. PMID 14617280. doi:10.1046/j.1524-475X.2003.11605.x. 
  9. ^ Andrew PJ, Mayer B (Aug 1999). "Enzymatic function of nitric oxide synthases". (review). Cardiovascular Research. 43 (3): 521–31. PMID 10690324. doi:10.1016/S0008-6363(99)00115-7. 
  10. ^ Goberdhan, Deborah C. I.; Wilson, Clive; Harris, Adrian L. (2016-04-12). "Amino Acid Sensing by mTORC1: Intracellular Transporters Mark the Spot". Cell Metabolism. 23 (4): 580–589. ISSN 1932-7420. PMC 5067300Freely accessible. PMID 27076075. doi:10.1016/j.cmet.2016.03.013. 
  11. ^ Kennedy, Brian K.; Lamming, Dudley W. (2016-06-14). "The Mechanistic Target of Rapamycin: The Grand ConducTOR of Metabolism and Aging". Cell Metabolism. 23 (6): 990–1003. ISSN 1932-7420. PMC 4910876Freely accessible. PMID 27304501. doi:10.1016/j.cmet.2016.05.009. 
  12. ^ Gokce N (Oct 2004). "L-arginine and hypertension". (review). The Journal of Nutrition. 134 (10 Suppl): 2807S–2811S; discussion 2818S–2819S. PMID 15465790. 
  13. ^ Rajapakse NW, De Miguel C, Das S, Mattson DL (Dec 2008). "Exogenous L-arginine ameliorates angiotensin II-induced hypertension and renal damage in rats". (primary). Hypertension. 52 (6): 1084–90. PMC 2680209Freely accessible. PMID 18981330. doi:10.1161/HYPERTENSIONAHA.108.114298. 
  14. ^ a b Dong JY, Qin LQ, Zhang Z, Zhao Y, Wang J, Arigoni F, Zhang W (Dec 2011). "Effect of oral L-arginine supplementation on blood pressure: a meta-analysis of randomized, double-blind, placebo-controlled trials". review. American Heart Journal. 162 (6): 959–965. PMID 22137067. doi:10.1016/j.ahj.2011.09.012. 
  15. ^ Shao A, Hathcock JN (2008). "Risk assessment for the amino acids taurine, L-glutamine and L-arginine". Regul Toxicol Pharmacol. 50 (3): 376–399. PMID 18325648. doi:10.1016/j.yrtph.2008.01.004. 
  16. ^ Alba-Roth J, Müller OA, Schopohl J, von Werder K (Dec 1988). "Arginine stimulates growth hormone secretion by suppressing endogenous somatostatin secretion". The Journal of Clinical Endocrinology and Metabolism. 67 (6): 1186–9. PMID 2903866. doi:10.1210/jcem-67-6-1186. 
  17. ^ U.S. National Library of Medicine (September 2009 Growth hormone stimulation test
  18. ^ Kanaley JA (2008). "Growth hormone, arginine and exercise". Curr Opin Clin Nutr Metab Care. 11 (1): 50–4. PMID 18090659. doi:10.1097/MCO.0b013e3282f2b0ad. 
  19. ^ Forbes SC, Bell GJ (2011). "The acute effects of a low and high dose of oral L-arginine supplementation in young active males at rest". Appl Physiol Nutr Metab. 36 (3): 405–11. PMID 21574873. doi:10.1139/h11-035. 
  20. ^ El-Hattab AW, Almannai M, Scaglia F (2017). "Arginine and citrulline for the treatment of MELAS syndrome". J Inborn Errors Metab Screen. 5. PMC 5519148Freely accessible. PMID 28736735. 
  21. ^ Gui S, Jia J, Niu X, Bai Y, Zou H, Deng J, Zhou R (Mar 2014). "Arginine supplementation for improving maternal and neonatal outcomes in hypertensive disorder of pregnancy: a systematic review". (review). Journal of the Renin-Angiotensin-Aldosterone System. 15 (1): 88–96. PMID 23435582. doi:10.1177/1470320313475910. 
  22. ^ Yang ZY, Wang F, Lu K, Li YH, Zhou Z (2016). "Arginine-containing desensitizing toothpaste for the treatment of dentin hypersensitivity: a meta-analysis". Clin Cosmet Investig Dent. 8: 1–14. PMC 4708190Freely accessible. PMID 26793006. doi:10.2147/CCIDE.S95660. 

External links[edit]