| enzyme | <biochemistry> A protein molecule produced by living organisms that catalyses chemical reactions of other substances without itself being destroyed or altered upon completion of the reactions. Enzymes are classified according to the recommendations of the Nomenclature Committee of the International Union of Biochemistry. Each enzyme is assigned a recommended name and an Enzyme Commission (EC) number. They are divided into six main groups, oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. (09 Oct 1997) |
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| enzyme activation | Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1) activation by ions (activators); 2) activation by cofactors (coenzymes); and 3) conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme. (12 Dec 1998) |
| enzyme analog | A synthetic macromolecule having enzymatic activity. Synonym: enzyme analog. (05 Mar 2000) |
| enzyme antagonist | An antimetabolite or inhibitor of enzyme action. (05 Mar 2000) |
| enzyme-catalyzed ligation | <enzyme> An enzyme-mediated joining of phosphodiester linkage of two stretches of DNA or RNA, or of peptide linkage of two polypeptides. (05 Mar 2000) |
| enzyme defect | A disorder resulting from a deficiency (or functional abnormality) of an enzyme. In 1902 Archibald Garrod first attributed a disease to an enzyme defect: an inborn error of metabolism. Today, newborns are routinely screened for certain enzyme defects such as PKU (phenylketonuria) and galactosaemia, an error in the handling (metabolism) of the sugar galactose. (12 Dec 1998) |
| enzyme derepression | Removing or turning off the inhibitor or inhibitors (molecules which repress or prevent other molecules from acting) enzyme so that enzyme activity can resume. (09 Oct 1997) |
| enzyme electrode | A type of biosensor. An enzyme is immobilised on the surface of an electrode, and when the enzyme catalyses its reaction, electrons are transferred from the reactant to the electrode, and a current is generated, which can then be measured. (14 Nov 1997) |
| enzyme immobilisation | The attachment of an enzyme to a solid matrix so that it cannot escape but can still act on its substrate. (09 Oct 1997) |
| enzyme immunoassay | The general term for an expanding technical arsenal of testing which allows a full range of quantitative analyses for both antigen and antibodies. These tests use colour-changed products of enzyme-substrate interaction (or inhibition) to measure the antigen-antibody reaction. Examples of EIA procedures (EMIT, ELISA, MAC, MEIA) follow. Acronym: EIA (05 Mar 2000) |
| enzyme inactivation | The disappearance of an enzyme's activity during in vitro conditions, such as during a lab preparation of the enzyme, where the enzyme is exposed to conditions not normally found within its environment inside a living cell (like different pH, excess or too little salt, temperature changes, etc.) (09 Oct 1997) |
| enzyme induction | An increase in enzyme secretion in response to an environmental signal. The classic example is the induction of _ galactosidase in E. Coli. (18 Nov 1997) |
| enzyme inhibition theory of narcosis | That narcotics inhibit respiratory enzymes by suppression of the formation of high energy phosphate bonds within the cell. (05 Mar 2000) |
| enzyme inhibitors | Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction. (12 Dec 1998) |
| enzyme-linked immunoabsorbent assay | <investigation> The enzyme-linked immunoabsorbent assay is serologic test used as a general screening tool for the detection of antibodies to the HIV virus. Reported as positive or negative. Since false positive tests due occur (for example recent flu shot), positives will require further evaluation using the western blot. ELISA technology links an a measurable enzyme to either an antigen or antibody. In this way, it can then measure the presence of an antibody or an antigen in the bloodstream. Acronym: ELISA (27 Sep 1997) |