Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is the first chemical step in photosynthesis, is called carboxylation, the addition of CO2 to a compound. Enzymes that catalyze decarboxylations are called decarboxylases or, the more formal term, carboxy-lyases (EC number 4.1.1).
5-Hydroxytryptophan (5-HTP), used medically as oxitriptan, is a naturally occurring amino acid and chemical precursor as well as a metabolic intermediate in the biosynthesis of the neurotransmitter serotonin.
Aromatic L-amino acid decarboxylase, also known as DOPA decarboxylase (DDC), tryptophan decarboxylase, and 5-hydroxytryptophan decarboxylase, is a lyase enzyme, located in region 7p12.2-p12.1.
Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The International Union of Biochemistry and Molecular Biology has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates.
The enzyme histidine decarboxylase is transcribed on chromosome 15, region q21.1-21.2, and catalyzes the decarboxylation of histidine to form histamine. In mammals, histamine is an important biogenic amine with regulatory roles in neurotransmission, gastric acid secretion and immune response. Histidine decarboxylase is the sole member of the histamine synthesis pathway, producing histamine in a one-step reaction. Histamine cannot be generated by any other known enzyme. HDC is therefore the primary source of histamine in most mammals and eukaryotes. The enzyme employs a pyridoxal 5'-phosphate (PLP) cofactor, in similarity to many amino acid decarboxylases. Eukaryotes, as well as gram-negative bacteria share a common HDC, while gram-positive bacteria employ an evolutionarily unrelated pyruvoyl-dependent HDC. In humans, histidine decarboxylase is encoded by the HDC gene.
Carboxy-lyases, also known as decarboxylases, are carbon–carbon lyases that add or remove a carboxyl group from organic compounds. These enzymes catalyze the decarboxylation of amino acids and alpha-keto acids.
Amino acid biosynthesis is the set of biochemical processes by which the amino acids are produced. The substrates for these processes are various compounds in the organism's diet or growth media. Not all organisms are able to synthesize all amino acids. For example, humans can synthesize 11 of the 20 standard amino acids. These 11 are called the non-essential amino acids.
An aromatic amino acid is an amino acid that includes an aromatic ring.
The enzyme adenosylmethionine decarboxylase catalyzes the conversion of S-adenosyl methionine to S-adenosylmethioninamine. Polyamines such as spermidine and spermine are essential for cellular growth under most conditions, being implicated in many cellular processes including DNA, RNA and protein synthesis. S-adenosylmethionine decarboxylase (AdoMetDC) plays an essential regulatory role in the polyamine biosynthetic pathway by generating the n-propylamine residue required for the synthesis of spermidine and spermine from putrescein. Unlike many amino acid decarboxylases AdoMetDC uses a covalently bound pyruvate residue as a cofactor rather than the more common pyridoxal 5'-phosphate. These proteins can be divided into two main groups which show little sequence similarity either to each other, or to other pyruvoyl-dependent amino acid decarboxylases: class I enzymes found in bacteria and archaea, and class II enzymes found in eukaryotes. In both groups the active enzyme is generated by the post-translational autocatalytic cleavage of a precursor protein. This cleavage generates the pyruvate precursor from an internal serine residue and results in the formation of two non-identical subunits termed alpha and beta which form the active enzyme.
The enzyme Acid-Induced Arginine Decarboxylase (AdiA), also commonly referred to as arginine decarboxylase, catalyzes the conversion of L-arginine into agmatine and carbon dioxide. The process consumes a proton in the decarboxylation and employs a pyridoxal-5'-phosphate (PLP) cofactor, similar to other enzymes involved in amino acid metabolism, such as ornithine decarboxylase and glutamine decarboxylase. It is found in bacteria and virus, though most research has so far focused on forms of the enzyme in bacteria. During the AdiA catalyzed decarboxylation of arginine, the necessary proton is consumed from the cell cytoplasm which helps to prevent the over-accumulation of protons inside the cell and serves to increase the intracellular pH. Arginine decarboxylase is part of an enzymatic system in Escherichia coli, Salmonella Typhimurium, and methane-producing bacteria Methanococcus jannaschii that makes these organisms acid resistant and allows them to survive under highly acidic medium.
The enzyme diaminopimelate decarboxylase (EC 4.1.1.20) catalyzes the cleavage of carbon-carbon bonds in meso-2,6-diaminoheptanedioate (diaminopimelate) to produce CO2 and L-lysine, the essential amino acid. It employs the cofactor pyridoxal phosphate, also known as PLP, which participates in numerous enzymatic transamination, decarboxylation and deamination reactions.
The enzyme chorismate synthase catalyzes the chemical reaction
In enzymology, an aromatic-amino-acid transaminase is an enzyme that catalyzes the chemical reaction
In enzymology, a tryptophan transaminase is an enzyme that catalyzes the chemical reaction
Biopterin-dependent aromatic amino acid hydroxylases (AAAH) are a family of aromatic amino acid hydroxylase enzymes which includes phenylalanine 4-hydroxylase, tyrosine 3-hydroxylase, and tryptophan 5-hydroxylase. These enzymes primarily hydroxylate the amino acids L-phenylalanine, L-tyrosine, and L-tryptophan, respectively.
In molecular biology, the Cys/Met metabolism PLP-dependent enzyme family is a family of proteins including enzymes involved in cysteine and methionine metabolism which use PLP (pyridoxal-5'-phosphate) as a cofactor.
In molecular biology, group III pyridoxal-dependent decarboxylases are a family of bacterial enzymes comprising ornithine decarboxylase EC 4.1.1.17, lysine decarboxylase EC 4.1.1.18 and arginine decarboxylase EC 4.1.1.19.
In molecular biology, group IV pyridoxal-dependent decarboxylases are a family of enzymes comprising ornithine decarboxylase EC 4.1.1.17, lysine decarboxylase EC 4.1.1.18, arginine decarboxylase EC 4.1.1.19 and diaminopimelate decarboxylaseEC 4.1.1.20. It is also known as the Orn/Lys/Arg decarboxylase class-II family.
In molecular biology, the group I pyridoxal-dependent decarboxylases, also known as glycine cleavage system P-proteins, are a family of enzymes consisting of glycine cleavage system P-proteins EC 1.4.4.2 from bacterial, mammalian and plant sources. The P protein is part of the glycine decarboxylase multienzyme complex (GDC) also annotated as glycine cleavage system or glycine synthase. The P protein binds the alpha-amino group of glycine through its pyridoxal phosphate cofactor, carbon dioxide is released and the remaining methylamine moiety is then transferred to the lipoamide cofactor of the H protein. GDC consists of four proteins P, H, L and T.
Indoleacetate decarboxylase (IAD) is a glycyl radical enzyme that catalyses the decarboxylation of indoleacetate to form skatole, which is a malodorous organic compound that gives animal faeces their characteristic smell. This decarboxylation is the last step of the tryptophan fermentation in some types of anaerobic bacteria.
