MeSH

A class of heterocyclic compounds that include a three-ring fused structure. Both aromatic or non-aromatic ring structures are included in this category.

Year introduced: 1998

A zinc-binding domain defined by the sequence Cysteine-X2-Cysteine-X(9-39)-Cysteine-X(l-3)-His-X(2-3)-Cysteine-X2-Cysteine -X(4-48)-Cysteine-X2-Cysteine, where X is any amino acid. The RING finger motif binds two atoms of zinc, with each zinc atom ligated tetrahedrally by either four cysteines or three cysteines and a histidine. The motif also forms into a unitary structure with a central cross-brace region and is found in many proteins that are involved in protein-protein interactions. The acronym RING stands for Really Interesting New Gene.

Year introduced: 2008

4-Hydroxy-1-(beta-D-ribofuranosyl)-2-pyridinone. Analog of uridine lacking a ring-nitrogen in the 3-position. Functions as an antineoplastic agent.

Year introduced: 1991(1975)

A dioxygenase with specificity for the oxidation of the indoleamine ring of TRYPTOPHAN. It is an extrahepatic enzyme that plays a role in metabolism as the first and rate limiting enzyme in the kynurenine pathway of TRYPTOPHAN catabolism.

Year introduced: 2006(1990)

A regulator of APOPTOSIS that functions as an E3 ubiquitin protein ligase. It contains three baculoviral IAP repeats in its N-terminal half, a CARD DOMAIN, and a RING finger domain at its C-terminus. It is highly expressed in fetal lung and kidney, and adult lymphoid tissues such as spleen, thymus, and peripheral blood lymphocytes. It functions in INFLAMMATION signaling, the INNATE IMMUNE RESPONSE, cell growth and proliferation, and metastasis of tumor cells.

Year introduced: 2018

3-Phenylchromones. Isomeric form of FLAVONOIDS in which the benzene group is attached to the 3 position of the benzopyran ring instead of the 2 position.

Year introduced: 1991(1975)

Aminobenzoate derivatives that contain an amino group attached to carbon number 3 or 5 of the benzene ring structure.

Year introduced: 2013

A reverse transcriptase inhibitor and ZALCITABINE analog in which a sulfur atom replaces the 3' carbon of the pentose ring. It is used to treat HIV disease.

Year introduced: 1997

A metabolite of THYROXINE, formed by the peripheral enzymatic monodeiodination of T4 at the 5 position of the inner ring of the iodothyronine nucleus.

Year introduced: 1985(1979)

oxytocin analog containing the oxytocin ring without the side chain; online & Index Medicus search OXYTOCIN/AA (75-82)

Date introduced: October 22, 1982

(GTP cyclohydrolase I) or GTP 7,8-8,9-dihydrolase (pyrophosphate-forming) (GTP cyclohydrolase II). An enzyme group that hydrolyzes the imidazole ring of GTP, releasing carbon-8 as formate. Two C-N bonds are hydrolyzed and the pentase unit is isomerized. This is the first step in the synthesis of folic acid from GTP. EC 3.5.4.16 (GTP cyclohydrolase I) and EC 3.5.4.25 (GTP cyclohydrolase II).

Year introduced: 1991(1975)

Compounds based on a seven-membered ring fused to a five-membered ring. Heat can rearrange them to NAPHTHALENES which have two fused six-membered rings. They are similar to guaiazulenes which are SESQUITERPENES with a six-membered ring fused to a five-membered ring.

Year introduced: 2006

PUROMYCIN derivative that lacks the methoxyphenylalanyl group on the amine of the sugar ring. It is an antibiotic with antineoplastic properties and can cause nephrosis.

Year introduced: 1991(1975)

ring shaped hexavalent betulinic acid−alpha-cyclodextrin conjugate

Date introduced: August 31, 2022

A nonapeptide that contains the ring of OXYTOCIN and the side chain of ARG-VASOPRESSIN with the latter determining the specific recognition of hormone receptors. Vasotocin is the non-mammalian vasopressin-like hormone or antidiuretic hormone regulating water and salt metabolism.

Year introduced: 1973(1963)

A dioxygenase with specificity for the oxidation of the indoleamine ring of TRYPTOPHAN. It is a LIVER-specific enzyme that is the first and rate limiting enzyme in the kynurenine pathway of TRYPTOPHAN catabolism.

Year introduced: 1968(1965)

Five-membered heterocyclic ring structures containing an oxygen in the 1-position and a nitrogen in the 3-position, in distinction from ISOXAZOLES where they are at the 1,2 positions.

2-(4-Amino-4-carboxybutyl)-1-(5-amino-5-carboxypentyl)-3,5-bis(3-amino-3-carboxypropyl)pyridinium. A rare amino acid found in elastin, formed by condensation of four molecules of lysine into a pyridinium ring.

Year introduced: 1991(1975)

A rare amino acid found in elastin, formed by condensation of four molecules of lysine into a pyridinium ring.

Year introduced: 1991(1975)

Date introduced: August 25, 2010