Citrulline

Structural formula
Structural formula of L - (+) - citrulline, the naturally occurring enantiomer
General
Surname	Citrulline
other names	N 5 - (aminocarbonyl) - L -ornithine N 5 -carbamoyl- L- ornithine ( S ) - N 5 -Carbamoyl-2,5-diaminopentanoic acid ( IUPAC )
Molecular formula	C 6 H 13 N 3 O 3
Brief description	white crystalline solid
External identifiers / databases
CAS number 372-75-8 [ L- citrulline] 13594-51-9 [ D- citrulline] 627-77-0 [ DL citrulline] EC number 206-759-6 ECHA InfoCard 100.006.145 PubChem 9750 ChemSpider 9367 DrugBank DB00155 Wikidata Q408641
Drug information
ATC code	A05 BA50
properties
Molar mass	175.19 g mol −1
Physical state	firmly
Melting point	214 ° C
solubility	good in water (200 g l −1 at 20 ° C)
safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

L - (+) - citrulline is a non- proteinogenic α- amino acid that is produced by plants and animals. Citrulline is named after the watermelon ( Citrullus vulgaris ) in which it is concentrated. Correspondingly, it also occurs in other cucurbits .

Citrulline is a homologue of L - homocitrulline , which is derived from L - lysine by carbamoylation .

Enantiomers

Citrulline has a stereocenter, so there are two chiral enantiomers .

Whenever the term "citrulline" is used in this article or in the scientific literature without any addition, it always means L - (+) - citrulline.

Enantiomers of citrulline
Surname	L - (+) - citrulline	D - (-) - citrulline
other names	( S ) -citrulline	( R ) -citrulline
Structural formula
CAS number	372-75-8	13594-51-9
	627-77-0 (racemate)
EC number	206-759-6	-
	211-012-2 (racemate)
ECHA info card	100.006.145	-
	100.010.012 (racemate)
PubChem	9750	637599
	833 (racemate)
DrugBank	DB00155	-
	- (racemate)
Wikidata	Q408641	Q27077003
	Q27102910 (racemate)

Occurrence

It is an intermediate product of the urea cycle . It normally arises from L - ornithine and carbamoyl phosphate, with its phosphate residue being split off by the ornithine carbamoyl transferase. It then reacts further with L - aspartate (anion of aspartic acid) to form L - argininosuccinate (enzyme: argininosuccinate synthetase) , splitting adenosine triphosphate . Aspartate is produced by transamination of oxaloacetate and introduces one of the two amino groups required for the urea produced into the urea cycle. The other is from carbamoyl phosphate.

physiology

Citrulline is increasingly excreted in the urine when people suffer from so-called nitrosative stress. Nitrosative stress is an endogenous exposure in the human body due to the nitrogen monoxide radical. In the urea cycle , arginine reacts more intensely with oxygen , producing NO and citrulline. Citrulline is therefore used as a marker for nitrosative stress in medical diagnostics .

Citrullination

As Citrullination the enzymatic conversion of arginine to citrulline is referred to. Peptidyl arginine deiminases (PAD) catalyze this post-translational modification , which takes place on certain proteins and peptides. These citrullinated proteins or peptides can be viewed by the immune system as foreign and, for example, attacked by antibodies . Citrullinated peptides, for example, play an important role in the pathogenesis of rheumatoid arthritis .

Web links

Commons : Citrulline  - collection of images, videos and audio files

Wikibooks: Urea Cycle  - Learning and Teaching Materials

Individual evidence

1. ↑ ^{a b c} Data sheet L (+) - Citrulline from Acros, accessed on January 6, 2008.
2. ↑ ^{a b} Data sheet L-Citrulline, ≥98% (TLC) from Sigma-Aldrich , accessed on February 13, 2013 ( PDF ).
3. ↑ M. Wada: About citrulline, a new amino acid in the pressed juice of watermelon, Citrullus vulgaris schrad. In: Biochem. Time. , 1930, 224 , pp. 420-429.
4. ↑ G. Klein (editor, author) Handbuch der Pflanzenanalyse, fourth volume / first half, special analysis, third part, organic substances III - special methods - tables , 1933, 840 , pp. 61-62, Springer-Verlag, 2. July 2013
5. ↑ External identifiers of or database links for L- homocitrulline : CAS number: 1190-49-4, EC number: 214-722-0 , ECHA InfoCard: 100.013.384 , PubChem : 65072 , ChemSpider : 58582 , Wikidata : Q18207833 .
6. ↑ Bodo Kuklinski: Das HWS-Trauma , Aurum Verlag, 2006.
7. ↑ P. Migliorini, F. Pratesi et al. a .: The immune response to citrullinated antigens in autoimmune diseases. In: Autoimmunity Reviews . Volume 4, Number 8, November 2005, pp. 561-564, doi : 10.1016 / j.autrev.2005.04.007 , PMID 16214096 (review).
8. ^ R. Yamada, A. Suzuki et al. a .: Citrullinated proteins in rheumatoid arthritis. In: Frontiers in bioscience: a journal and virtual library. Volume 10, January 2005, pp. 54-64, PMID 15574347 (review).
9. ↑ T. Gazitt, C. Lood, KB Elkon: Citrullination in Rheumatoid Arthritis-A Process Promoted by Neutrophil Lysis? In: Rambam Maimonides medical journal. Volume 7, number 4, October 2016, p., Doi : 10.5041 / RMMJ.10254 , PMID 27824546 , PMC 5101001 (free full text) (review).