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C6H13O3N3 An amino acid formed in the synthesis of arginine from ornithine.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(also called α-amino-δ-ureidovaleric acid), H2NCONH(CH2)3CH(NH2)COOH, a natural amino acid.

Citrulline exists in the optically active L- and D-forms and in the racemic DL-form. L-citrulline is found as a free compound in the juice of watermelons and a number of other plants, in the tubers of legumes, and in the tissues of mammals (liver, kidney, brain, muscles, and blood). Citrulline is not a component of natural proteins. Citrulline is separated from enzymatic hydrolysates of casein as a result of arginine splitting. In many organisms, citrulline participates in the ornithine cycle, in which it serves as an intermediate in the biosynthesis of arginine from ornithine. In plants, citrulline also participates in nitrogen fixation.


Meister, A. Biokhimiia aminokislot. Moscow, 1961. (Translated from English.)
Lehninger, A. Biokhimiia: Molekuliarnye osnovy struktury i funktsii kletki. Moscow, 1976. (Translated from English.)
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
He does know that a typical 4-ounce serving of watermelon (about 10 watermelon balls) has about 150 milligrams of citrulline. But he can't say how much citrulline is needed to have Viagra-like effects.
Thai reference was different in that most amino acid concentrations were higher, except for the same ranges of citrulline, valine, proline, methionine, and lower arginine.
ADTS/ DHTS, citrulline, and PE(18:0/22:4) were all found to be important metabolic features differentiating patients with complicated versus noncomplicated course of febrile neutropenia at the start of fever (d0 and d1).
Caldwell, "Therapeutic use of citrulline in cardiovascular disease," Cardiovascular Drug Reviews, vol.
Among auxiliary assays, increase in use of measurements of citrulline level in the blood, cytofluorographic analysis of peripheral immune cell population, cytokine profiles, and the quantitation of distinct gene set changes have been observed (33-35).
Plasma citrulline levels demonstrated a progressive downward trend with levels consistently below 10 micromol/L from this period in December 2015 onwards.
Caption: Figure 1: The levels of (a) L-arginine, (b) L-ornithine, (c) L- citrulline, (d) glutamine, (e) glutamate, (f) GABA, (g) glutamate/GABA ratio, and (h) L-citrulline/L-arginine ratio in the postrhinal cortex (POR), entorhinal cortex (EC), brain stem (BS), striatum (ST), and cerebellum (CE) in young and old rats.
The targets for ACPA are citrullinated peptides, that is, peptides that underwent posttranslation conversion of arginine to citrulline residues catalyzed by peptidylarginine deiminases (PAD).
[1] described an increase in plasma citrulline and arginine after the intake of 3.3 kg (fresh weight) of ripe watermelon.
Peptidylarginine deiminase belongs to a family of enzymes that convert the arginine residues of proteins into citrulline. These enzymes are expressed in most mammalian tissues.
In the urea cycle, OTC combines ornithine and carbamoyl phosphate to form citrulline. Thus, an OTC enzyme deficiency leads to decreased production of citrulline, interruption of the urea cycle, increased orotic acid which is produced by excess carbamoyl phosphate, and ultimately life-threatening hyperammonemia due to the inability to excrete excess nitrogen.