Editing Arginine (section)

==Sources==
===Production===
It is traditionally obtained by [[hydrolysis]] of various cheap sources of protein, such as [[gelatin]].<ref>{{cite journal|title=d-Arginine Hydrochloride| vauthors = Brand E, Sandberg M |journal=Org. Synth.|year=1932|volume=12|page=4|doi=10.15227/orgsyn.012.0004}}</ref> It is obtained commercially by fermentation. In this way, 25-35 g/liter can be produced, using glucose as a carbon source.<ref name=Ullmann>{{Ullmann|first1=Karlheinz|last1=Drauz|first2=Ian|last2=Grayson|first3=Axel|last3=Kleemann|first4=Hans-Peter|last4=Krimmer|first5=Wolfgang|last5=Leuchtenberger|first6=Christoph|last6=Weckbecker |display-authors=3| name-list-style = vanc |year=2006|doi=10.1002/14356007.a02_057.pub2|title=Amino Acids}}</ref>

===Dietary sources===
Arginine is classified as a semiessential or conditionally [[essential amino acid]], depending on the developmental stage and health status of the individual.<ref name="tapiero">{{cite journal |vauthors=Tapiero H, Mathé G, Couvreur P, Tew KD | title = L-Arginine | journal = Biomedicine & Pharmacotherapy | date = November 2002 | volume = 56 | issue = 9 | pages = 439–445 | doi = 10.1016/s0753-3322(02)00284-6 | pmid = 12481980 | department = (review) }}</ref> Preterm infants are unable to synthesize arginine internally, making the amino acid nutritionally essential for them.<ref>{{cite journal | vauthors = Wu G, Jaeger LA, Bazer FW, Rhoads JM | title = Arginine deficiency in preterm infants: biochemical mechanisms and nutritional implications | journal = The Journal of Nutritional Biochemistry | volume = 15 | issue = 8 | pages = 442–51 | date = August 2004 | pmid = 15302078 | doi = 10.1016/j.jnutbio.2003.11.010 | department = (review) | doi-access = free }}</ref> Most healthy people do not need to supplement with arginine because it is a component of all protein-containing foods<ref name=mayo>{{cite web|title=Drugs and Supplements Arginine|website=[[Mayo Clinic]]|url=http://www.mayoclinic.org/drugs-supplements/arginine/background/hrb-20058733|access-date=15 January 2015}}</ref> and can be synthesized in the body from [[glutamine]] via [[citrulline]].<ref>{{Cite book|url=https://books.google.com/books?id=3qexy5Se3SoC&pg=PA76|title=Dietitian's Handbook of Enteral and Parenteral Nutrition| vauthors = Skipper A |date=1998|publisher=Jones & Bartlett Learning|isbn=978-0-8342-0920-6|pages=76|language=en}}</ref><ref name=":1">{{Cite book|url=https://books.google.com/books?id=1nRbFrSil40C&pg=PA48|title=Enteral Nutrition| vauthors = Borlase BC |date=1994|publisher=Jones & Bartlett Learning|isbn=978-0-412-98471-6|pages=48|language=en}}</ref> Additional, dietary arginine is necessary for otherwise healthy individuals temporarily under physiological stress, for example during recovery from burns, injury or sepsis,<ref name=":1" /> or if either of the major sites of arginine biosynthesis, the [[small intestine]] and [[kidney]]s, have reduced function, because the small bowel does the first step of the synthesizing process and the kidneys do the second.<ref name=":0" />

Arginine is an essential amino acid for birds, as they do not have a [[urea cycle]].<ref>{{Cite book|url=https://books.google.com/books?id=dFb7AwAAQBAJ&pg=PA45|title=A Biochemical Approach to Nutrition| vauthors = Freedland RA, Briggs S |date=2012-12-06|publisher=Springer Science & Business Media|isbn=9789400957329|pages=45|language=en}}</ref> For some carnivores, for example cats, dogs<ref>{{Cite book|url=https://books.google.com/books?id=LWC6PChg9ZEC&pg=PA65|title=Nutrient Requirements of Dogs |date=1985|publisher=National Academies Press|isbn=978-0-309-03496-8|pages=65|language=en}}</ref> and ferrets, arginine is essential,<ref name=":0" /> because after a meal, their highly efficient [[protein catabolism]] produces large quantities of [[ammonia]] which need <!-- quantities is plural -->to be processed through the urea cycle, and if not enough arginine is present, the resulting ammonia toxicity can be lethal.<ref name=":2">{{Cite book|url=https://books.google.com/books?id=mh7yCQAAQBAJ&pg=PA232|title=Nutrition and Disease Management for Veterinary Technicians and Nurses| vauthors = Wortinger A, Burns K |date=2015-06-11|publisher=John Wiley & Sons|isbn=978-1-118-81108-5|pages=232|language=en}}</ref> This is not a problem in practice, because meat contains sufficient arginine to avoid this situation.<ref name=":2" />

Animal sources of arginine include meat, dairy products, and eggs,<ref>{{Cite book|url=https://books.google.com/books?id=p_YtDwAAQBAJ&pg=PA240|title=Nutrition for Sport, Exercise, and Health| vauthors = Spano MA, Kruskall LJ, Thomas DT | name-list-style = vanc |date=2017-08-30|publisher=Human Kinetics|isbn=978-1-4504-1487-6|pages=240|language=en}}</ref><ref name=":3">{{Cite book|url=https://books.google.com/books?id=kzKqMAkJw3UC&pg=PA75|title=Bioactive Dietary Factors and Plant Extracts in Dermatology| vauthors = Watson RR, Zibadi S |date=2012-11-28|publisher=Springer Science & Business Media|isbn=978-1-62703-167-7|pages=75|language=en}}</ref> and plant sources include seeds of all types, for example grains, beans, and nuts.<ref name=":3" />

===Biosynthesis===
Arginine is synthesized from [[citrulline]] in the urea cycle by the sequential action of the cytosolic enzymes [[argininosuccinate synthetase]] and [[argininosuccinate lyase]]. This is an energetically costly process, because for each molecule of [[Argininosuccinic acid|argininosuccinate]] that is synthesized, one molecule of [[adenosine triphosphate]] (ATP) is hydrolyzed to [[adenosine monophosphate]] (AMP), consuming two ATP equivalents.{{cn|date=July 2024}}

The pathways linking arginine, [[glutamine]], and [[proline]] are bidirectional. Thus, the net use or production of these amino acids is highly dependent on cell type and developmental stage.{{cn|date=July 2024}}

[[File:Arginine biosynthesis pathway.png|thumb|Arginine biosynthesis|center|500px]]

Arginine is made by the body as follows. The [[epithelial cell]]s of the [[small intestine]] produce citrulline, primarily from [[glutamine]] and [[glutamate]], which is secreted into the bloodstream which carries it to the [[proximal tubule cell]]s of the [[kidney]], which extract the citrulline and convert it to arginine, which is returned to the blood. This means that impaired small bowel or renal function can reduce arginine synthesis and thus create a dietary requirement for arginine. For such a person, arginine would become "essential".

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 increase the production of [[Nitric oxide synthase#iNOS|inducible nitric oxide synthase (NOS)]]. This allows citrulline, a byproduct of the NOS-catalyzed production of nitric oxide, to be recycled to arginine in a pathway known as the citrulline to nitric oxide (citrulline-NO) or arginine-citrulline pathway. This is demonstrated by the fact that, in many cell types, nitric oxide synthesis can be supported to some extent by citrulline, and not just by arginine. This recycling is not quantitative, however, because citrulline accumulates in nitric oxide producing cells along with [[nitrate]] and [[nitrite]], the stable end-products of nitric oxide breakdown.<ref>{{cite journal | vauthors = Morris SM | title = Enzymes of arginine metabolism | journal = The Journal of Nutrition | volume = 134 | issue = 10 Suppl | pages = 2743S–2747S; discussion 2765S–2767S | date = October 2004 | pmid = 15465778 | doi = 10.1093/jn/134.10.2743S | department = (review) | doi-access = free }}</ref>