 | |
 | |
| Names | |
|---|---|
| IUPAC name 2-Amino-5-(carbamoylamino)pentanoic acid[1] | |
| Identifiers | |
| |
3D model (JSmol) | |
| 1725417, 1725415D, 1725416L | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| DrugBank |
|
| ECHA InfoCard | 100.006.145 |
| EC Number |
|
| 774677L | |
| KEGG |
|
| MeSH | Citrulline |
| UNII |
|
| |
| |
| Properties | |
| C6H13N3O3 | |
| Molar mass | 175.188 g·mol−1 |
| Appearance | White crystals |
| Odor | Odourless |
| logP | −1.373 |
| Acidity (pKa) | 2.508 |
| Basicity (pKb) | 11.489 |
| Thermochemistry | |
| 232.80 J K−1 mol−1 | |
Std molar entropy(S⦵298) | 254.4 J K−1 mol−1 |
| Related compounds | |
Related alkanoic acids | |
Related compounds | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Theorganic compoundcitrulline is anon-essential α-amino acid.[2] Its name is derived fromcitrullus, theLatin word forwatermelon. Although named and described bygastroenterologists since the late 19th century, it was first isolated from watermelon in 1914 byJapanese researchers Yatarō Koga (古賀彌太郎) and Ryō Ōtake (大嶽了)[3][4] and further codified by Mitsunori Wada ofTokyo Imperial University in 1930.[5][6][7]It has theformula H2NC(O)NH(CH2)3CH(NH2)CO2H. It is a key intermediate in theurea cycle, the pathway by which mammals excreteammonia by converting it intourea. Citrulline is also produced as a byproduct of theenzymatic production ofnitric oxide from the amino acidarginine, catalyzed bynitric oxide synthase.[8]
Citrulline can be derived from:
Citrulline is made fromornithine andcarbamoyl phosphate in one of the central reactions in the urea cycle. It is also produced fromarginine as a byproduct of the reaction catalyzed byNOS family (NOS;EC 1.14.13.39).[9] It is also prevalent intrichohyalin at the inner rootsheath and medulla of hair follicles, where it is synthesized from arginine.[10]Arginine is first oxidized intoN-hydroxyl-arginine, which is then further converted to citrulline concomitant with release of nitric oxide.
Citrulline is also made byenterocytes of the small intestine.[2][11]
Citrulline is a metabolic intermediate within theurea cycle, which is 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. In the yeast species Saccharomyces cerevisiae, citrulline is a metabolic intermediate in the latter, cytosolic half of the arginine biosynthesis pathway.[12]
Several proteins contain citrulline as a result of apost-translational modification. These citrulline residues are generated by a family of enzymes calledpeptidylarginine deiminases (PADs), which convert arginine into citrulline in a process calledcitrullination or deimination with the help of calcium ions. Proteins that normally contain citrulline residues includemyelin basic protein (MBP),filaggrin, and severalhistone proteins, whereas other proteins, such asfibrin andvimentin are susceptible to citrullination during cell death and tissueinflammation.
Circulating citrulline concentration is abiomarker of intestinal functionality.[13][14]
L-citrulline is sold as adietary supplement, usually in powder form. Advocates suggest that since L-citrulline boosts nitric oxide production,[citation needed] helping arterial function and thus blood flow throughout the body, this might be helpful in treating or preventing various ailments.
Some of these assertions are based on animal studies, and like most dietary supplement claims have not been endorsed by theFood and Drugs Administration.[16]
L-citrulline is added to certainenergy drinks such asReign and touted for a claimedthermogenic effect.[17]
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