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L-Arginine
Identifiers
CAS number 74-79-3 Yes check.svgY
PubChem 6322
ChemSpider 227
SMILES
InChI
InChI key ODKSFYDXXFIFQN-UHFFFAOYAT
Properties
Molecular formula C6H14N4O2
Molar mass 174.2 g mol−1
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Arginine (abbreviated as Arg or R)[1] is an α-amino acid. The L-form is one of the 20 most common natural amino acids. Its codons are CGU, CGC, CGA, CGG, AGA, and AGG. In mammals, arginine is classified as a semiessential or conditionally essential amino acid, depending on the developmental stage and health status of the individual.[2] Infants are unable to meet their requirements and thus arginine is nutritionally essential for infants.[3] Arginine was first isolated from a lupin seedling extract in 1886 by the Swiss chemist Ernst Schultze.

Contents

Structure

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.

Delocalization of charge in guanidinium group of L-Arginine

With a pKa of 12.48, the guanidinium group is positively charged 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.

Sources

Dietary sources

Arginine is a conditionally nonessential amino acid, meaning most of the time it can be manufactured by the human body, and does not need to be obtained directly through the diet. The biosynthetic pathway however does not produce sufficient arginine, and some must still be consumed through diet. Individuals who have poor nutrition or certain physical conditions may be advised to increase their intake of foods containing arginine. Arginine is found in a wide variety of foods, including[4]:

Biosynthesis

Arginine is synthesized from citrulline by the sequential action of the cytosolic enzymes argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL). This is energetically costly, as the synthesis of each molecule of argininosuccinate requires hydrolysis of adenosine triphosphate (ATP) to adenosine monophosphate (AMP); i.e., two ATP equivalents.

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. Consequently, 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.[5]

Function

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][6][7] Arginine,[8] taken in combination with proanthocyanidins[9] or yohimbine[10], has also been used as a treatment for erectile dysfunction.

The benefits and functions attributed to oral supplementation of L-arginine include:

In proteins

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.

As a precursor

Arginine is the immediate precursor of 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. For being a precursor of NO, (relaxes blood vessels), arginine is used in many 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.

Treatment of herpes simplex virus

A low ratio of arginine to lysine may be of benefit in the treatment of herpes simplex virus. For more information, refer to Herpes - Treatment.

Possible increased risk of death after supplementation following heart attack

A clinical trial found that patients taking an L-arginine supplement following a heart attack didn't improve in their vascular tone or their hearts' ability to pump. In fact, more patients who were taking L-arginine died than those taking a placebo and the study was stopped early with the recommendation the supplement not be used by heart attack patients.[14][15][16] The supplement is still widely marketed.

Lung inflammation and asthma

The Mayo Clinic web page on L-arginine reports that inhalation of L-arginine can increase lung inflammation and worsen asthma.[17]

Growth hormone

Arginine may boost the production of growth hormone[18], although this has not been proven.[citation needed]

MELAS syndrome

Several trials delved into effects of L-agrinine in MELAS syndrome, a mitochondrial disease.[19][20][21][22]

See also

AAKG

References

  1. ^ IUPAC-IUBMB Joint Commission on Biochemical Nomenclature. "Nomenclature and Symbolism for Amino Acids and Peptides". Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc. http://www.chem.qmul.ac.uk/iupac/AminoAcid/. Retrieved 2007-05-17. 
  2. ^ a b c Tapiero, H.; et al. (November 2002). "L-Arginine". Biomedicine and Pharmacotherapy 56 (9): 439–445 REVIEW. PMID 12481980. 
  3. ^ Wu, G.; et al. (August 2004). "Arginine deficiency in preterm infants: biochemical mechanisms and nutritional implications". Journal of Nutritional Biochemistry 15 (8): 332–451 REVIEW. PMID 15302078. 
  4. ^ "L-Arginine Supplements Nitric Oxide Scientific Studies Food Sources". http://www.keysupplements.com/articles/L-Arginine-Supplements-Nitric-Oxide-Scientific-Studies.htm. Retrieved 2007-02-20. 
  5. ^ Free review.png Enzymes of arginine metabolism J Nutr. 2004 Oct; 134(10 Suppl): 2743S-2747S; PMID 15465778 Free text
  6. ^ a b c Stechmiller, J.K.; et al. (February 2005). "Arginine supplementation and wound healing". Nutrition in Clinical Practice 20 (13): 52–61 REVIEW. PMID 16207646. 
  7. ^ a b c Witte, M.B.; Barbul, A (Nov-Dec 2003). "Arginine physiology and its implication for wound healing". Wound Repair and Regeneration 11 (6): 419–423 REVIEW. PMID 14617280. 
  8. ^ "L-Arginine, the Prosexual Nutrient with Numerous Health Benefits". http://www.smart-publications.com/sexual_health/l-arginine.php. Retrieved 2009-01-01. 
  9. ^ Stanislavov, R. and Nikolova. 2003. Treatment of Erectile Dysfunction with Pycnogenol and L-arginine. Journal of Sex and Marital Therapy, 29(3): 207 – 213.
  10. ^ Lebret, T., Hervéa, J. M., Gornyb, P., Worcelc, M. and Botto, H. 2002. Efficacy and Safety of a Novel Combination of L-Arginine Glutamate and Yohimbine Hydrochloride: A New Oral Therapy for Erectile Dysfunction. European Urology 41(6): 608-613.
  11. ^ Andrew, P.J.; Myer, B. (August 15 1999). "Enzymatic function of nitric oxide synthases". Cardiovascular Research 43 (3): 521–531 REVIEW. doi:10.1016/S0008-6363(99)00115-7. PMID 10690324.  [1]
  12. ^ Gokce, N.. (October 2004). "L-Arginine and hypertension". Journal of Nutrition 134 (10 Suppl): 2807S-2811S REVIEW. PMID 15465790. 
  13. ^ Rajapakse, N.W.; et al. (December 2008). "Exogenous L-arginine ameliorates angiotensin II-induced hypertension and renal damage in rats". Hypertension 52 (6): 1084–1090. doi:10.1161/HYPERTENSIONAHA.108.114298. PMID 18981330.  [2]
  14. ^ Medical College of Georgia. "Diabetes Makes It Hard For Blood Vessels To Relax." ScienceDaily 1 February 2008. 1 February 2008
  15. ^ Arginine Therapy in Acute Myocardial Infarction JAMA. 2006 Jan; Vol.295 #1: 58-64; PMID 16391217 Abstract
  16. ^ This study has been discussed in some detail in : "Reverse Heart Disease Now" by Stephen T Sinatra MD and James C Roberts MD, publ. Wiley 2006 ISBN 0-471-74704-1 at pp 111-113.
  17. ^ Sapienza MA, Kharitonov SA, Horvath I, Chung KF, Barnes PJ. "Effect of inhaled L-arginine on exhaled nitric oxide in normal and asthmatic subjects." Thorax. 1998 Mar;53(3):172-5.
  18. ^ Alba-Roth J, Müller O, Schopohl J, von Werder K (1988). "Arginine stimulates growth hormone secretion by suppressing endogenous somatostatin secretion". J Clin Endocrinol Metab 67 (6): 1186–9. doi:10.1210/jcem-67-6-1186. PMID 2903866. 
  19. ^ Koga Y, Akita Y, Junko N, Yatsuga S, Povalko N, Fukiyama R, Ishii M, Matsuishi T (June 2006). "Endothelial dysfunction in MELAS improved by l-arginine supplementation". Neurology 66 (11): 1766–9. doi:10.1212/01.wnl.0000220197.36849.1e. PMID 16769961. http://www.neurology.org/cgi/pmidlookup?view=long&pmid=16769961. 
  20. ^ Koga Y (November 2008). "[L-arginine therapy on MELAS]" (in Japanese). Rinsho Shinkeigaku 48 (11): 1010–2. PMID 19198147. 
  21. ^ Koga Y, Akita Y, Nishioka J, Yatsuga S, Povalko N, Katayama K, Matsuishi T (2007). "MELAS and L-arginine therapy". Mitochondrion 7 (1-2): 133–9. doi:10.1016/j.mito.2006.11.006. PMID 17276739. http://linkinghub.elsevier.com/retrieve/pii/S1567-7249(06)00227-3. 
  22. ^ Finsterer J (November 2009). "Management of mitochondrial stroke-like-episodes". Eur. J. Neurol. 16 (11): 1178–84. doi:10.1111/j.1468-1331.2009.02789.x. PMID 19780807. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1351-5101&date=2009&volume=16&issue=11&spage=1178. 

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