Citrulline

Citrulline
Names
	IUPAC name 2-Amino-5-(carbamoylamino)pentanoic acid
Identifiers
CAS Number	627-77-0 ; 13594-51-9 (D) ; 372-75-8 (L) ;
3D model (JSmol)	Interactive image;
Beilstein Reference	1725417, 1725415 D, 1725416 L
ChEBI	CHEBI:18211 ;
ChEMBL	ChEMBL444814 ;
ChemSpider	810 ; 553200 D ; 9367 L ;
DrugBank	DB00155 ;
ECHA InfoCard	100.006.145
EC Number	211-012-2;
Gmelin Reference	774677 L
IUPHAR/BPS	722;
KEGG	D07706 ;
MeSH	Citrulline
PubChem CID	833; 637599 D; 9750 L;
UNII	1OYO2NV4NM ; KNS2VUH6P2 (D) ; 29VT07BGDA (L) ;
CompTox Dashboard (EPA)	DTXSID80883373 ;
	InChI InChI=1S/C6H13N3O3/c7-4(5(10)11)2-1-3-9-6(8)12/h4H,1-3,7H2,(H,10,11)(H3,8,9,12) Key: RHGKLRLOHDJJDR-UHFFFAOYSA-N ;
	SMILES NC(CCCNC(N)=O)C(O)=O;
Properties
Chemical formula	C6H13N3O3
Molar mass	175.188 g·mol−1
Appearance	White crystals
Odor	Odourless
log P	−1.373
Acidity (pKa)	2.508
Basicity (pKb)	11.489
Thermochemistry
Heat capacity (C)	232.80 J K−1 mol−1
Std molar; entropy (S⦵298)	254.4 J K−1 mol−1
Related compounds
Related alkanoic acids	N-Acetylaspartic acid; Aceglutamide; N-Acetylglutamic acid; Pivagabine;
Related compounds	Bromisoval; Carbromal;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

The organic compound citrulline is an α-amino acid. Its name is derived from citrullus, the Latin word for watermelon. Although named and described by gastroenterologists since the late 19th century, it was first isolated from watermelon in 1914 by Japanese researchers Yatarō Koga (古賀彌太郎) and Ryō Ōtake (大嶽了) and further codified by Mitsunori Wada of Tokyo Imperial University in 1930. It has the formula H₂NC(O)NH(CH₂)₃CH(NH₂)CO₂H. It is a key intermediate in the urea cycle, the pathway by which mammals excrete ammonia by converting it into urea. Citrulline is also produced as a byproduct of the enzymatic production of nitric oxide from the amino acid arginine, catalyzed by nitric oxide synthase.