THE FOLLOWING IS COPIED FROM WIKIPEDIA.
IT WILL SOON BE EDITED
Arginine (abbreviated as Arg or R)[1] is
an α-amino acid. It was first isolated in 1886.[2] The L-form is one of the 20 most common natural amino acids. At the
level of molecular genetics, in the structure of the messenger ribonucleic acid mRNA, CGU, CGC, CGA, CGG, AGA, and AGG, are
the triplets of nucleotide bases or codons that codify for arginine during protein synthesis.
In mammals, arginine is classified as a
semiessential or conditionally essential amino acid, depending on the developmental stage and health status of the individual.[3]
Preterm infants are unable to synthesize or create arginine internally, making the amino acid nutritionally essential for
them.[4] There are some conditions that put an increased demand on the body for the synthesis of L-arginine, including surgical
or other trauma, sepsis and burns.[citation needed] Arginine was first isolated from a lupin seedling extract in 1886 by the
Swiss chemist Ernst Schultze.
In general, most people do not need to
take arginine supplements because the body usually produces enough.[2]
StructureThe 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
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.
[edit] Sources[edit] Dietary sourcesArginine
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[5]:
Animal sources
dairy products (e.g., cottage cheese, ricotta,
milk, yogurt, whey protein drinks), beef, pork (e.g., bacon, ham), gelatin , poultry (e.g. chicken and turkey light meat),
wild game (e.g. pheasant, quail), seafood (e.g., halibut, lobster, salmon, shrimp, snails, tuna)
Plant sources
wheat germ and flour, buckwheat, granola,
oatmeal, peanuts, nuts (coconut, pecans, cashews, walnuts, almonds, Brazil nuts, hazelnuts, pinenuts), seeds (pumpkin, sesame,
sunflower), chick peas, cooked soybeans, Phalaris canariensis (canaryseed or ALPISTE)
[edit] BiosynthesisArginine is synthesized
from citrulline 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. Taking an excess of arginine
essentially gives more energy by saving ATPs that can be used elsewhere.
Citrulline can be derived from multiple
sources:
from arginine via nitric oxide synthase
(NOS)
from ornithine via catabolism of proline
or glutamine/glutamate
from asymmetric dimethylarginine (ADMA)
via DDAH
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]
[edit] FunctionArginine plays an important
role in cell division, the healing of wounds, removing ammonia from the body, immune function, and the release of hormones.[3][7][8]
The benefits and functions attributed to
oral supplementation of L-arginine include:
Precursor for the synthesis of nitric oxide
(NO)[9]
Reduces healing time of injuries (particularly
bone)[7][8]
Quickens repair time of damaged tissue[7][8]
Helps decrease blood pressure[10][11]
[edit] ProteinsThe 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.
[edit] PrecursorArginine 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.[3]
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.
[edit] Treatment of dentin hypersensitivityArginine
(8%) in dental products (e.g., toothpaste) provides effective relief from sensitive teeth by depositing a dentin-like mineral,
containing calcium and phosphate, within the dentin tubules and in a protective layer on the dentin surface.[12]
[edit] Treatment of herpes simplex virusAn
unproven claim is that 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 also see journal article.[13]
[edit] Possible increased risk of death
after supplementation following heart attackA clinical trial found that patients taking an L-arginine supplement following
a heart attack found no change in the heart's vascular tone or decrease in the symptoms of congestive heart failure (the heart's
ability to pump). In fact, six more patients who were taking L-arginine died than those taking a placebo resulting in early
termination of the study with the recommendation that the supplement not be used by heart attack patients.[14][15][16] These
findings suggest L-arginine is not beneficial post-heart-attack.
[edit] Potential medical uses[edit] Lung
inflammation and asthmaThe Mayo Clinic web page on L-arginine reports that inhalation of L-arginine can increase lung inflammation
and worsen asthma.[17]
[edit] Growth hormoneArginine may stimulate
the secretion of growth hormone,[18] and is used in growth hormone stimulation tests.[19] However, more recent research suggests
that oral preparations of L-arginine are ineffective at increasing growth hormone levels despite being effective at increasing
plasma levels of L-arginine.[20][medical citation needed]
[edit] MELAS syndromeSeveral trials delved
into effects of L-arginine in MELAS syndrome, a mitochondrial disease.[21][22][23][24]
[edit] SepsisCellular arginine biosynthetic
capacity determined by activity of argininosuccinate synthetase (AS) is induced by the same mediators of septic response —
endotoxin and cytokines — that induce nitric oxide synthase (NOS), the enzyme responsible for nitric oxide synthesis.[25]
[edit] Malate saltThe malate salt of arginine
can also be used during the treatment of alcoholic hepatitis and advanced cirrhosis.[26]
[edit] Pre-eclampsiaA preliminary study
of supplementation with L-arginine and antioxidant vitamins showed that this combination may help to combat abnormally high
blood pressure during high risk pregnancies.[27]
[edit] HypertensionA recent meta-analysis
showed that L-arginine reduces blood pressure with pooled estimates of 5.4/2.7 mmHg for SBP/DBP. [28]
[edit] Erectile DysfunctionArginine taken
in combination with proanthocyanidins[29] or yohimbine,[30] has also been used as a treatment for erectile dysfunction.
[edit] See alsoAAKG
Canavanine and canaline are toxic analogs
of arginine and ornithine.
[edit] References1.^ 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. http://www.chem.qmul.ac.uk/iupac/AminoAcid/.
Retrieved 2007-05-17.
2.^ a b Mayo Clinic
3.^ a b c Tapiero, H.; et al. (November
2002). "L-Arginine". Biomedicine and Pharmacotherapy 56 (9): 439–445 REVIEW. PMID 12481980.
4.^ 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. DOI:10.1016/j.jnutbio.2003.11.010. PMID 15302078.
5.^ "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.
6.^ Morris Jr SM (October 2004). "Enzymes
of arginine metabolism.". The Journal of nutrition 134 (10 Suppl): 2743S–2747S. PMID 15465778. http://www.nutrition.org/cgi/content/full/134/10/2743S.
7.^ a b c Stechmiller, J.K.; et al. (February
2005). "Arginine supplementation and wound healing". Nutrition in Clinical Practice 20 (13): 52–61 REVIEW. DOI:10.1177/011542650502000152.
PMID 16207646.
8.^ 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.
DOI:10.1046/j.1524-475X.2003.11605.x. PMID 14617280.
9.^ 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]
10.^ Gokce, N.. (October 2004). "L-Arginine
and hypertension". Journal of Nutrition 134 (10 Suppl): 2807S–2811S REVIEW. PMID 15465790.
11.^ 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. PMC 2680209. PMID 18981330. //www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2680209.
Retrieved 2009-11-29. [2]
12.^ Petrou, I.; et al. (2009). "A breakthrough
therapy for dentin hypersensitivity: how dental products containing 8% arginine and calcium carbonate work to deliver effective
relief of sensitive teeth.". The Journal of Clinical Dentisry 20 (1): 23–31. PMID 19489189.
13.^ Takeshi Naito, Hiroshi Irie, Kazuko
Tsujimoto, Keiko Ikeda, Tsutomu Arakawa, A. Hajime Koyama (April 2009). "Antiviral effect of arginine against herpes simplex
virus type 1". International Journal of Molecular Medicine (International Journal of Molecular Medicine) 23 (4): 495–499.
DOI:10.3892/ijmm_00000156. PMID 19288025. http://www.spandidos-publications.com/ijmm/article.jsp?article_id=ijmm_23_4_495.
Retrieved 2010-10-18.
14.^ Medical College of Georgia. "Diabetes
Makes It Hard For Blood Vessels To Relax." ScienceDaily 1 February 2008. 1 February 2008
15.^ Schulman SP, Becker LC, Kass DA, Champion
HC, Terrin ML, Forman S, Ernst KV, Kelemen MD et al. (January 2006). "L-arginine therapy in acute myocardial infarction: the
Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) randomized clinical trial.". JAMA: the Journal of the
American Medical Association 295 (1): 58–64. DOI:10.1001/jama.295.1.58. PMID 16391217. http://jama.ama-assn.org/cgi/content/short/295/1/58.
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.^ U.S. National Library of Medicine
(September 2009). Growth hormone stimulation test
20.^ Does L-Arginine Increase Growth Hormone
Levels?
21.^ 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.
22.^ Koga Y (November 2008). "[L-arginine
therapy on MELAS]" (in Japanese). Rinsho Shinkeigaku 48 (11): 1010–2. PMID 19198147.
23.^ 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.
24.^ 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.
25.^ MORRIS SM (1995). ROLE OF ARGININE
SYNTHESIS IN SURGICAL SEPSIS. Crisp Data Base National Institutes Of Health. Archived from the original on 26 February 2010.
http://toxnet.nlm.nih.gov/. Retrieved 2010-02-22.
26.^ Tissot-Favre A, Brette R (May–June
1970). "Therapeutic effects of arginine malate in alcoholic cirrhosis". Therapie 25 (3): 629–33. PMID 5431854.
27.^ Vadillo-Ortega F et al. (2011). "Effect
of supplementation during pregnancy with L-arginine and antioxidant vitamins in medical food on pre-eclampsia in high risk
population: randomised controlled trial". British Medical Journal 342: d2901–d2901. DOI:10.1136/bmj.d2901. http://www.bmj.com/content/342/bmj.d2901.
28.^ Dong JY, Qin LQ, Zhang Z, Zhao Y,
Wang J, Arigoni F, Zhang W. (2011). "Effect of oral L-arginine supplementation on blood pressure: a meta-analysis of randomized,
double-blind, placebo-controlled trials". American Heart Journal 162 (6): 959–965. DOI:10.1016/j.ahj.2011.09.012. PMID
22137067.
29.^ Stanislavov R., Nikolova V (2003).
"Treatment of Erectile Dysfunction with Pycnogenol and L-arginine". Journal of Sex and Marital Therapy 29 (3): 207–213.
DOI:10.1080/00926230390155104. PMID 12851125.
30.^ Lebret, T.; Hervéa, J. M.; Gornyb,
P.; Worcelc, M.; 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. DOI:10.1016/S0302-2838(02)00175-6. PMID
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