| cyclic compound | Any compound in which the constituent atoms, or any part of them, form a ring. Used mainly in organic chemistry where: 1) numerous compound's contain rings of carbon atoms (carbocyclic compound's) or carbon atoms plus one or more atoms of other types (heterocyclic compound's), usually nitrogen, oxygen, or sulfur; 2) where the atoms in the ring are all of the same element (homocyclic or isocyclic compound); 3) where the ring is saturated or contains nonconjugated double bonds (alicyclic compound), the compound is similar in properties to the corresponding acyclic compound (e.g., cyclohexane resembles hexane); 4) where the ring contains conjugated double bonds in a closed loop in which there are 4n + 2 (where n is an integer) delocalised π electrons (Huckel's rule) (aromatic compound; e.g., benzene, pyridine), it is more stable than the corresponding saturated ring and exhibits unusual chemical properties characteristic of itself and not of other types of rings or of acyclic compound's. These aromatic compounds have the ability to sustain an induced ring current. Synonym: closed chain compound, ring compound. (05 Mar 2000) |
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| cyclic esotropia | Periodic convergent strabismus often occurring every 48 hours. Synonym: alternate day strabismus. (05 Mar 2000) |
| cyclic GMP | <molecular biology> 3'5' cyclic ester of GMP. A second messenger generated by guanylyl cyclase. See: ANP, Nitric oxide. (18 Nov 1997) |
| cyclic GMP-dependent protein kinases | <enzyme> A group of enzymes that are dependent on cyclic GMP and catalyses the phosphorylation of serine or threonine residues of proteins. Registry number: EC 2.7.10.- (12 Dec 1998) |
| cyclic GMP sensitive 3'-exoribonuclease | <enzyme> Degradation of newly synthesised RNA in cells of bacillus brevis is mediated primarily by above enzyme Registry number: EC 3.1.14.- Synonym: cgmp-exoribonuclease (26 Jun 1999) |
| cyclic guanosine monophosphate | A cyclic version of the nucleotide guanosine monophosphate. It plays a role in communicating vision from the eyes to the brain. (09 Oct 1997) |
| cyclic haematopoiesis | An autosomal recessive, inherited immunodeficiency of gray collie dogs characterised by overwhelming recurrent bacterial infections, bleeding, and coat colour dilution. Synonym: gray collie syndrome. (05 Mar 2000) |
| cyclic imp | <chemical> Inosine cyclic 3',5'-(hydrogen phosphate). An inosine nucleotide which acts as a mild inhibitor of the hydrolysis of cyclic AMP and cyclic GMP and as an inhibitor of cat heart cyclic AMP phosphodiesterase. Chemical name: Inosine, cyclic 3',5'-(hydrogen phosphate) (12 Dec 1998) |
| cyclic inositol phosphate | 1, 2 cyclic derivatives of inositol phosphatide that are invariably formed during enzymic hydrolysis of phosphatidyl inositol species. Have been proposed as second messengers in hormone activated pathways. (18 Nov 1997) |
| cyclic neutropenia | Neutropenia recurring at regular intervals (14 to 45 days), in association with various types of infectious diseases, e.g., stomatitis, cutaneous ulcers, furuncles, arthritis, and others. Synonym: cyclic neutropenia. (05 Mar 2000) |
| cyclic nucleotide | A nucleoside monophosphate in which the phosphoryl group is linked twice to the sugar moiety; e.g., adenosine 3',5'-cyclic monophosphate (cAMP). (05 Mar 2000) |
| cyclic nucleotide-regulated protein kinases | <enzyme> A group of enzymes that catalyses the phosphorylation of serine or threonine residues of proteins and is dependent on cyclic nucleotides. Registry number: EC 2.7.10.- (12 Dec 1998) |
| cyclic peptide | A peptide that forms a ring structure; e.g., tyrocidin A, an antibiotic, is a cyclic decapeptide; valinomycin is a cyclic depsipeptide. (05 Mar 2000) |
| cyclic phosphate | An activator of phosphorylase kinase and an effector of other enzymes, formed in muscle from ATP by adenylate cyclase and broken down to 5'-AMP by a phosphodiesterase; sometimes referred to as the "second messenger." A related compound (2',3') is also known. Synonym: cyclic adenylic acid, cyclic AMP, cyclic phosphate. Acronym: cAMP (05 Mar 2000) |
| cyclic phosphoric acid | In general, a linear polymer of phosphoric acid residues in pyrophosphate linkage in which the a and ω residues are similarly linked to make one endless loop or cyclic compound, specifically, a generic term applied to compounds in which one phosphoric acid residue is esterified to two hydroxyl groups of a single carbon chain, as in adenosine 3',5'-phosphoric acid, adenosine 2',3'-phosphoric acid, etc. (05 Mar 2000) |