CitrullineThe organic compoundcitrulline is a non-essential 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 and Ryō Ōtake, and further codified in 1930.
Post-translational modificationPost-translational modifications (PTMs) are the covalent processes of changing proteins following their synthesis, and release from ribosomes. PTMs are reversible editing events used and carried out in the overall process of post-translational regulation – the control of the levels of active protein; an irreversible event is proteolysis (protein degradation). PTMs enable the protein's function to be diversified and extended beyond the dictates of transcription.
Rheumatoid arthritisType of autoimmune arthritisMedical conditionRheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involved, with the same joints typically involved on both sides of the body. The disease may also affect other parts of the body, including skin, eyes, lungs, heart, nerves, and blood.
ArginineArginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the amino and guanidino groups are protonated, resulting in a cation. Only the L-arginine (symbol Arg or R) enantiomer is found naturally. Arg residues are common components of proteins.
Protein foldingProtein folding is the physical process by which a protein, after synthesis by a ribosome as a linear chain of amino acids, changes from an unstable random coil into a more ordered three-dimensional structure. This structure permits the protein to become biologically functional or active. The folding of many proteins begins even during the translation of the polypeptide chain.
Amino acidOrganic compounds containing amine and carboxylic groupsStructure of a typical L-alpha-amino acid in the "neutral" formAmino acids are organic compounds that contain both amino and carboxylic acidfunctional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life.
Arginine deiminaseArginine deiminase (EC3.5.3.6) is an enzyme characterised from Streptococcus species that catalyzes the hydrolysis of the amino acid, arginine, to citrulline and ammonia: arginine H2ONH3citrulline In murine cytotoxic macrophages, this reaction leads to the production of nitrite. The enzyme has been studied as an anti-tumor drug. This enzyme is a hydrolase, one acting on carbon-nitrogen bonds other than peptide bonds, specifically in linear amidines.
Nitric oxide synthaseNitric oxide synthases (NOSs) are a family of enzymes catalyzing the production of nitric oxide (NO) from L-arginine. NO is an important cellular signaling molecule. It helps modulate vascular tone, insulin secretion, airway tone, and peristalsis, and is involved in angiogenesis and neural development. It may function as a retrograde neurotransmitter.Urea cycleThe urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea (NH2)2CO from ammonia (NH3). Animals that use this cycle, mainly amphibians and mammals, are called ureotelic. The urea cycle converts highly toxic ammonia to urea for excretion. This cycle was the first metabolic cycle to be discovered by Hans Krebs and Kurt Henseleit in 1932, five years before the discovery of the TCA cycle.
Multiple sclerosisMultiple sclerosis (MS) is an autoimmune disease where the immune system attacks myelin, the insulating cover of nerve cells in the human body, causing damage to one's own central nervous system. It is a type of demyelinating disease, where the nervous system's ability to transmit signals is damaged. Symptoms can be physical, mental, or both, including double vision, vision loss, eye pain, muscle weakness, loss of sensation and coordination.
Genetic codeGenetic code is a set of rules used by living cells to translate information encoded within genetic material (DNA or RNA sequences of nucleotide triplets or codons) into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time.
KetoneIn organic chemistry, a ketone is an organic compound with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group−C(=O)− (a carbon-oxygen double bond C=O). A ketone derived from an alkane is an alkanone. The simplest ketone is acetone (where R and R' are methyl), with the formula (CH3)2CO. Many ketones are of great importance in biology and industry.
Protein-arginine deiminaseIn enzymology, a protein-arginine deiminase (PAD) (EC 3.5.3.15) is an enzyme that catalyzes a form of post translational modification called arginine de-imination or citrullination: protein L-arginine + H2O ⇌ {\displaystyle \rightleftharpoons } protein L-citrulline + NH3 Thus, the two substrates of this enzyme are protein L-arginine (arginine residue inside a protein) and H2O, whereas its two products are protein L-citrulline and NH3: This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in linear amidines.*As an Amazon Associate I earn from qualifying purchases.