Definition of Citrulline

Citrulline: A non-standard amino acid that is not normally present in protein. Citrulline is created in the body as an intermediate in the conversion of the amino acid ornithine to arginine in a metabolic pathway called the urea cycle.

Citrulline was first isolated from watermelon. The term citrulline was coined in 1930 from citrullus, the Latin name of the watermelon.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=24640
Last Editorial Review: 6/14/2012