Editing Arginine (section)

== Function ==
Arginine plays an important role in [[cell division]], [[wound healing]], removing ammonia from the body, [[immune function]],<ref>{{Cite book|url=https://books.google.com/books?id=Hc3rCgAAQBAJ&pg=PA17|title=The Metabolic Challenges of Immune Cells in Health and Disease| vauthors = Mauro C, Frezza C |date=2015-07-13|publisher=Frontiers Media SA|isbn=9782889196227|pages=17|language=en}}</ref> and the release of hormones.<ref name="tapiero"/><ref>{{cite journal | vauthors = Stechmiller JK, Childress B, Cowan L | title = Arginine supplementation and wound healing | journal = Nutrition in Clinical Practice | volume = 20 | issue = 1 | pages = 52–61 | date = February 2005 | pmid = 16207646 | doi = 10.1177/011542650502000152 | department = (review) }}</ref><ref>{{cite journal | vauthors = Witte MB, Barbul A | title = Arginine physiology and its implication for wound healing | journal = Wound Repair and Regeneration | volume = 11 | issue = 6 | pages = 419–23 | year = 2003 | pmid = 14617280 | doi = 10.1046/j.1524-475X.2003.11605.x | s2cid = 21239136 | department = (review) }}</ref> It is a precursor for the synthesis of [[nitric oxide]] (NO),<ref>{{cite journal | vauthors = Andrew PJ, Mayer B | title = Enzymatic function of nitric oxide synthases | journal = Cardiovascular Research | volume = 43 | issue = 3 | pages = 521–31 | date = August 1999 | pmid = 10690324 | doi = 10.1016/S0008-6363(99)00115-7 | department = (review) | doi-access = free}}</ref> making it important in the regulation of [[blood pressure]].<ref>{{cite journal | vauthors = Gokce N | title = L-arginine and hypertension | journal = The Journal of Nutrition | volume = 134 | issue = 10 Suppl | pages = 2807S–2811S; discussion 2818S–2819S | date = October 2004 | pmid = 15465790 | doi = 10.1093/jn/134.10.2807S | doi-access = free }}</ref><ref>{{cite journal | vauthors = Kibe R, Kurihara S, Sakai Y et al | title = Upregulation of colonic luminal polyamines produced by intestinal microbiota delays senescence in mice | journal = Scientific Reports | volume = 4 | issue = 4548 | date = 2014 | page = 4548 | pmid = 24686447| doi = 10.1038/srep04548 | pmc = 4070089 | bibcode = 2014NatSR...4.4548K | doi-access = free }}</ref> Arginine is necessary for T-cells to function in the body, and can lead to their deregulation if depleted.<ref>{{Cite journal |last1=Banerjee |first1=Kasturi |last2=Chattopadhyay |first2=Agnibha |last3=Banerjee |first3=Satarupa |date=2022-07-01 |title=Understanding the association of stem cells in fetal development and carcinogenesis during pregnancy |journal=Advances in Cancer Biology - Metastasis |language=en |volume=4 |pages=100042 |doi=10.1016/j.adcanc.2022.100042 |s2cid=248485831 |issn=2667-3940|doi-access=free}}</ref><ref>{{Cite journal |last1=Rodriguez |first1=Paulo C. |last2=Quiceno |first2=David G. |last3=Ochoa |first3=Augusto C. |date=2006-10-05 |title=l-arginine availability regulates T-lymphocyte cell-cycle progression |url=https://doi.org/10.1182/blood-2006-06-031856 |journal=Blood |volume=109 |issue=4 |pages=1568–1573 |doi=10.1182/blood-2006-06-031856 |issn=0006-4971 |pmc=1794048 |pmid=17023580}}</ref>

===Proteins===
Arginine's side chain is [[Amphiphile|amphipathic]], because at physiological pH it contains a positively charged guanidinium group, which is highly polar, at the end of a hydrophobic [[Aliphatic compound|aliphatic]] hydrocarbon chain. Because globular proteins have hydrophobic interiors and hydrophilic surfaces,<ref>{{Cite book |title=Biochemistry|url=https://archive.org/details/biochemistry0003math|url-access=registration| vauthors = Mathews CK, Van Holde KE, Ahern KG |date=2000|publisher=Benjamin Cummings|isbn=978-0805330663|edition=3rd|location=San Francisco, Calif.|pages=[https://archive.org/details/biochemistry0003math/page/180 180]|oclc=42290721}}</ref> arginine is typically found on the outside of the protein, where the hydrophilic head group can interact with the polar environment, for example taking part in [[hydrogen bond]]ing and [[Salt bridge (protein and supramolecular)|salt bridges.]]<ref name=":4">{{Cite book|url=https://books.google.com/books?id=CN9sYPJdXs4C&pg=PA326|title=Bioinformatics for Geneticists: A Bioinformatics Primer for the Analysis of Genetic Data| vauthors = Barnes MR |date=2007-04-16|publisher=John Wiley & Sons|isbn=9780470026199 |pages=326 }}</ref> For this reason, it is frequently found at the interface between two proteins.<ref>{{Cite book|url=https://books.google.com/books?id=hbd8dlG7zkIC&pg=PA13|title=Protein-protein Recognition| vauthors = Kleanthous C |date=2000|publisher=Oxford University Press|isbn=9780199637607|pages=13|language=en}}</ref> The aliphatic part of the side chain sometimes remains below the surface of the protein.<ref name=":4" />

Arginine residues in proteins can be deiminated by PAD enzymes to form citrulline, in a [[post-translational modification]] process called [[citrullination]].This is important in fetal development, is part of the normal immune process, as well as the control of gene expression, but is also significant in [[autoimmune disease]]s.{{sfn|Griffiths|Unwin|2016|p=275}} Another post-translational modification of arginine involves [[methylation]] by protein [[methyltransferase]]s.{{sfn|Griffiths|Unwin|2016|p=176}}

===Precursor===
Arginine is the immediate precursor of nitric oxide, an important signaling molecule which can act as a [[Second messenger system|second messenger]], as well as an intercellular messenger which regulates vasodilation, and also has functions in the immune system's reaction to infection.{{cn|date=July 2024}}

Arginine is also a precursor for [[urea]], [[ornithine]], and [[agmatine]]; is necessary for the synthesis of [[creatine]]; and can also be used for the synthesis of [[polyamine]]s (mainly through ornithine and to a lesser degree through agmatine, citrulline, and glutamate). 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 <small>L</small>-arginine is considered a sign of a healthy [[endothelium]].<ref name="pmid32781796">{{cite journal |vauthors=Gambardella J, Khondkar W, Morelli MB, Wang X, Santulli G, Trimarco V |title=Arginine and Endothelial Function |journal=Biomedicines |volume=8 |issue=8 |date=August 2020 |page=277 |pmid=32781796 |pmc=7460461 |doi=10.3390/biomedicines8080277 |url= |doi-access=free }}</ref>