| RELP | restriction fragment length polymorphism |
|---|---|
| RELV | restriction fragment length variant |
| RFLP | restriction fragment length polymorphism |
| DNA | Deoxyribo-Nucleic Acid |
| DDS | damaged disc syndrome; dendrodendritic synaptosome; dental distress syndrome; depressed DNA synthesi... |
| restriction nuclease | <enzyme, molecular biology> Class of bacterial enzymes that cut DNA at specific sites. In bacteria their function is to destroy foreign DNA, such as that of bacteriophages (host DNA is specifically modified at these sites). Type I restriction endonucleases occur as a complex with the methylase and a polypeptide that binds to the recognition site on DNA. They are often not very specific and cut at a remote site. Type II restriction endonucleases are the classic experimental tools. They have very specific recognition and cutting sites. The recognition sites are short, 4-8 nucleotides and are usually palindromic sequences. Because both strands have the same sequence running in opposite directions the enzymes make double stranded breaks, which, if the site of cleavage is off centre, generates fragments with short single stranded tails, these can hybridise to the tails of other fragments and are called sticky ends. They are generally named according to the bacterium from which they were isolated (first letter of genus name and the first two letters of the specific name). The bacterial strain is identified next and multiple enzymes are given Roman numerals. For example the two enzymes isolated from the R strain of E. Coli are designated Eco RI and Eco RII. (10 Mar 1998) |
|---|---|
| restriction site | A sequence in DNA that can be recognised and cut by a specific restriction enzyme. (12 Dec 1998) |
| restriction-site polymorphism | DNA polymorphism in which the sequence of one form of the polymorphism contains a recognition site for a particular endonuclease, but the sequence of the other form lacks such a site. (05 Mar 2000) |
| MHC restriction | <immunology> Restriction on interaction between cells of the immune system because of the requirement to recognise foreign antigen is association with MHC antigens (major histocompatibility antigens). Thus, cytotoxic T-cells will only kill virally infected cells that have the same Class I antigens as themselves, whereas helper T-cells respond to foreign antigen associated with Class II antigens. (18 Nov 1997) |
| host restriction-modification | A bacterial system where the bacterium is able to destroy invading DNA from a bacteriophage (virus which infects bacteria) while at the same time preventing the destruction of their own DNA. The phage DNA is cleaved by a restriction enzyme made by the bacterium, the bacterial DNA is modified (usually with methylation) so that the enzyme will not destroy it. (09 Oct 1997) |
| lactase restriction | An inherited trait in which there is low lactase activity and thus there is defective lactose intestinal metabolism. Compare: lactase persistence. (05 Mar 2000) |
| acetyl-activating enzyme | A ligase that catalyses the reaction of acetate and CoA and ATP to form AMP, pyrophosphate, and acetyl-CoA. A key step in the activation of acetate. Synonym: acetate thiokinase, acetate-CoA ligase, acetyl-activating enzyme, acetyl-CoA synthetase. (05 Mar 2000) |
| acyl-activating enzyme | <enzyme> Fatty acid thiokinase (long-chain), a ligase forming acyl-CoA, AMP, and pyrophosphate from long-chain fatty acids, ATP, and coenzyme A. Activity is independent of phosphatidylcholine Registry number: EC 6.2.1.3 Synonym: acyl-activating enzyme, dodecanoyl-CoA synthetase, fatty acid thiokinase (long chain), acid-coenzyme a ligase, fatty acid-CoA ligase, acyl-CoA synthetase, acyl-CoA ligase, coash ligase, ciprofibroyl-CoA synthetase, pristanoyl-CoA synthetase, palmityl CoA synthetase, palmitoyl CoA synthetase, palmitoyl CoA ligase, fatty acyl-CoA synthetase, very long chain fatty acid acyl-CoA synthetase, vlcfa acyl-CoA synthetase, nafenopin-CoA ligase, palmitoyl-CoA synthase, faa2 gene product, faa2p protein, vlacs enzyme (26 Jun 1999) |
| adaptive enzyme | Inducible enzyme, an enzyme that can be detected in a growing culture of a microorganism, after the addition of a particular substance (inducer) to the culture medium, but was not detectable prior to the addition and can act on the inducer. A prototype is the beta-galactosidase of Escherichia coli, synthesised upon the addition of various galactosides, whether or not these are good substrates. Compare: constitutive enzyme. Synonym: adaptive enzyme. (05 Mar 2000) |
| allosteric enzyme | <biochemistry, chemistry> A regulatory enzyme whose activity is modified by the noncovalent binding of a particular metabolite at a site (the allosteric site) other than the active site. (09 Oct 1997) |
| amino acid activating enzyme | <enzyme> Enzymes catalyzing the formation of a specific aminoacyl-tRNA from an amino acid and adenosine 5'-triphosphate with the concomitant formation of adenosine 5'-monophosphate and pyrophosphate. Synonym: amino acid activating enzyme, aminoacyl-tRNA ligases. (05 Mar 2000) |
| angiotensin-converting enzyme | <enzyme> This hydrolase enzyme cleaves the decapeptide angiotensin I (biologically inactive) to form active angiotensin II by angiotensin-converting enzyme which removes a dipeptide (histidylleucine) from angiotensin I. Angiotensin II causes contraction of vascular smooth muscle and thus raises blood pressure and stimulates aldosterone release from the adrenal glands. Angiotensin is finally broken down by angiotensinases. Elevations in angiotensin converting enzyme are seen sarcoidosis, histoplasmosis, alcoholic cirrhosis, asbestosis, berylliosis, diabetes, Hodgkin's disease, hyperthyroidism, amyloidosis, primary biliary cirrhosis, idiopathic pulmonary fibrosis, pulmonary embolism, scleroderma, silicosis, tuberculosis, Gaucher's disease and leprosy. The normal values are 18 to 67 U/ml over 20 years of age (people under 20 have higher levels). Drugs that inhibit ACE are used to treat hypertension and congestive heart failure. See: angiotensin-converting enzyme inhibitor Acronym: ACE (12 Aug 2000) |
| angiotensin-converting enzyme inhibitor | <pharmacology> A class of drugs used in the treatment of hypertension and heart failure. They exert their haemodynamic effect mainly by inhibiting the renin-angiotensin system and produce a reduction of peripheral arterial resistance. They also modulate sympathetic nervous system activity and increase prostaglandin synthesis. They cause mainly vasodilation and mild natriuresis without affecting heart rate and contractility. (14 Aug 2000) |
| angiotensin-converting enzyme secretase | <enzyme> Converts ace from a membrane-bound to a soluble form; not inhibited by thiol, serine or acid enzyme inhibitor but is inhibited by edta and 1,10-phenanthroline Registry number: EC 3.4.99.- Synonym: ace secretase (26 Jun 1999) |
| Antibody Directed Enzyme Prodrug Therapy | <pharmacology> A method for targeting a drug to a specific tissue, in which the targeting agent and the drug are administered separately. The drug is designed to be inactive (a prodrug) until it is converted by an enzyme, which is the targeting agent. The enzyme is coupled to an antibody that directs it to the tissue of interest. When the enzyme arrives at the tissue, the prodrug is activated only at that site, sparing other tissues from potentially toxic side effects. Acronym: ADEPT (14 Nov 1997) |