| Victor-Michaelis-Menten equation | <chemistry> Equation derived from a simple kinetic model for a single-substrate non-cooperative enzyme-catalyzed reaction that successfully accounts for the hyperbolic adsorption isotherm) relationship between substrate concentration and reaction rate. V = Vmax x S/(S + Km), where V is the initial velocity of the reaction, Km is the Michaelis constant, Vmax is the maximum rate approached by very high substrate concentrations and S is the initial substrate concentration. Similar equations can be derived for conditions in which the product is present and for multisubstrate enzymes. Synonym: Victor-Michaelis-Menten equation. (12 Jul 2000) |
|---|---|
| Michaelis complex | Binary complex of an enzyme. (05 Mar 2000) |
| Michaelis constant | <chemistry> The true dissociation constant for the enzyme-substrate binary complex in a single-substrate rapid equilibrium enzyme-catalyzed reaction (usually symbolised by Ks), the concentration of the substrate at which half the true maximum velocity of an enzyme-catalyzed reaction is achieved (when velocities are measured under initial rate and steady state conditions). The ratio of rate constants (k2 + k3)/k1 in the single-substrate enzyme-catalyzed reaction: E + S &dblarr; ES &dblarr; E + products where E represents the free enzyme, S is the substrate, and ES is the central binary complex. The expression for the Michaelis constant will be more complex for multisubstrate reactions. An apparent Michaelis constant is a constant determined either under conditions that are not strictly steady state and initial rate or one that varies with the concentration of one or more cosubstrates. See: Michaelis-Menten equation. Synonym: Michaelis-Menten constant. (05 Mar 2000) |
| Michaelis-Gutmann body | <radiology> A rounded homogenous or concentrically laminated body, 1 to 10 u in diameter, containing calcium apatite and iron; found within macrophages in the bladder wall in malakoplakia. (12 Jul 2000) |
| Michaelis, Leonor | <person> German-U.S. Chemist, 1875-1949. See: Michaelis-Gutmann body, Michaelis constant, Michaelis-Menten constant, Michaelis-Menten equation, Michaelis-Menten hypothesis. (05 Mar 2000) |
| Michaelis-Menten constant | <chemistry> The true dissociation constant for the enzyme-substrate binary complex in a single-substrate rapid equilibrium enzyme-catalyzed reaction (usually symbolised by Ks), the concentration of the substrate at which half the true maximum velocity of an enzyme-catalyzed reaction is achieved (when velocities are measured under initial rate and steady state conditions). The ratio of rate constants (k2 + k3)/k1 in the single-substrate enzyme-catalyzed reaction: E + S &dblarr; ES &dblarr; E + products where E represents the free enzyme, S is the substrate, and ES is the central binary complex. The expression for the Michaelis constant will be more complex for multisubstrate reactions. An apparent Michaelis constant is a constant determined either under conditions that are not strictly steady state and initial rate or one that varies with the concentration of one or more cosubstrates. See: Michaelis-Menten equation. Synonym: Michaelis-Menten constant. (05 Mar 2000) |
| Michaelis-Menten equation | <chemistry> Equation derived from a simple kinetic model for a single-substrate non-cooperative enzyme-catalyzed reaction that successfully accounts for the hyperbolic adsorption isotherm) relationship between substrate concentration and reaction rate. V = Vmax x S/(S + Km), where V is the initial velocity of the reaction, Km is the Michaelis constant, Vmax is the maximum rate approached by very high substrate concentrations and S is the initial substrate concentration. Similar equations can be derived for conditions in which the product is present and for multisubstrate enzymes. Synonym: Victor-Michaelis-Menten equation. (12 Jul 2000) |
| Michaelis-Menten hypothesis | <chemistry> That a complex is formed between an enzyme and its substrate (the O'Sullivan-Tompson hypothesis), which complex then decomposes to yield free enzyme and the reaction products (Brown hypothesis), the latter rate determining the overall rate of substrate-product conversion. See: Michaelis-Menten constant, Michaelis-Menten equation. (05 Mar 2000) |
| Abbott's stain | <technique> Spores are stained blue with alkaline methylene blue; bodies of the bacilli become pink with eosin counterstain. (05 Mar 2000) |
| aceto-orcein stain | <technique> A stain used for chromosomes in air-dried or squashed cytologic material. (05 Mar 2000) |
| acid-fast stain | <technique> A staining technique used to determine the cell wall property of a microorganism. After stained with dye such as hot carbolfuschin, an acid-fast organism, (for example Mycobacterium species) will retain the colour in its cell wall after being washed with acid-alcohol. (13 Nov 1997) |
| acid stain | <technique> A dye in which the anion is the coloured component of the dye molecule, e.g., sodium eosinate (eosin). (05 Mar 2000) |
| Ag-AS stain | <technique> A stain for the acid protein component of nucleolar regions which are active or which were transcriptionally active in the preceding interphase; uses silver nitrate, ammoniacal silver, and formalin. Synonym: Ag-AS stain. (05 Mar 2000) |
| Albert's stain | <technique> A stain for diphtheria bacilli and their metachromatic granules; contains toluidine blue, methyl green, glacial acetic acid, alcohol, and distilled water. (05 Mar 2000) |
| Altmann's anilin-acid fuchsin stain | <technique> A mixture of picric acid, anilin, and acid fuchsin which stains mitochondria crimson against a yellow background. (05 Mar 2000) |