Citrulline
Common name	citrulline
Systematic name	2-amino-5-(carbamoyl amino)pentanoic acid
Chemical formula	C6H13N3O3
Molecular mass	175.2 g mol−1
CAS number	372-75-8
Disclaimer and references

The chemical compound citrulline is an α-amino acid (AA). Citrulline was first isolated from watermelon. It was named after citrullus which is the latin for watermelon. In science, a common name is any name by which a species or other concept is known that is not the official scientific name. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... The molecular mass (abbreviated MM) of a substance, called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Image File history File links Citrulline. ... A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Binomial name Citrullus lanatus (Thunb. ...

Synthesis

Citrulline is made from ornithine and carbamoyl phosphate in one of the central reactions in the urea cycle. It is also produced from Arginine as a by-product of the reaction catalyzed by NOS family. Ornithine is an amino acid, whose structure is: NH2-CH2-CH2-CH2-CHNH2-COOH Ornithine is one of the products of the action of the enzyme arginase on L-arginine, creating urea. ... Carbamoyl phosphate is a molecule that is involved in ridding the body of excess nitrogen in the urea cycle, and also in the synthesis of pyrimidines. ... The Urea Cycle is a cycle of biochemical reactions occurring in many animal organisms that produces urea from ammonia. ... Arginine (Arg) is an α-amino acid. ... The nitric oxide synthases (NOS) are a group of enzymes (EC 1. ...

Function

Citrulline, while being an amino acid, is not built into proteins during protein synthesis, as it is not coded for by DNA, yet several proteins are known to contain citrulline. These citrulline residues are generated by a family of enzymes called peptidylarginine deiminases (PADs), which convert Arginine into citrulline. Proteins that normally contain citrulline residues include MBP, fillagrin and several histone proteins, while other proteins, like fibrin and vimentin can get citrullinated during cell-death and tissue inflammation. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... An overview of protein synthesis. ... The general structure of a section of DNA Deoxyribonucleic acid (DNA) is a nucleic acid —usually in the form of a double helix— that contains the genetic instructions specifying the biological development of all cellular forms of life, and most viruses. ... Myelin basic protein (MBP) is a protein believed to be important in the process of myelination of nerves in the central nervous system (CNS). ... In biology, histones are the chief proteins of chromatin. ...

Patients with rheumatoid arthritis often (at least 80% of them) develop an immune response against proteins containing citrulline. Although the origin of this immune response is not known, detection of antibodies reactive with citrulline containing proteins or peptides is now becoming an important help in the diagnosis of rheumatoid arthritis . Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints. ... Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints. ...