| isoelectric period | The period occurring in the electrocardiogram between the end of the S wave and the beginning of the T wave during which electrical forces are acting in directions such as to neutralise each other so that there is no difference in potential under the two electrodes. (05 Mar 2000) |
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| isoelectric point | <biochemistry> The pH at which a protein carries no net charge. Below the isoelectric point proteins carry a net positive charge, above it a net negative charge. Due to a preponderance of weakly acid residues in almost all proteins, they are nearly all negatively charged at neutral pH. The isoelectric point is of significance in protein purification because it is the pH at which solubility is often minimal and at which mobility in an electrofocusing system is zero (and therefore the point at which the protein will accumulate). (18 Nov 1997) |
| isoelectric zone | The range of H-ion concentration (pH) over which isoelectric precipitation occurs. (05 Mar 2000) |
| isoenergetic | Exerting equal force; equally active. Synonym: isodynamogenic. (05 Mar 2000) |
| isoenzyme | <biochemistry> Variants of enzymes that catalyse the same reaction, but owing to differences in amino acid sequence can be distinguished by techniques such as electrophoresis or isoelectric focusing. Different tissues often have different isoenzymes. The sequence differences generally confer different enzyme kinetic parameters that can sometimes be interpreted as fine tuning to the specific requirements of the cell types in which a particular isoenzyme is found. (15 Oct 1997) |
| isoenzyme electrophoresis | Electrophoretic separation of serum enzymes; separation of lactate dehydrogenase and creatine phosphokinase is commonly used for diagnosis of acute myocardial infarction. (05 Mar 2000) |
| isoenzymes | One of various structurally related forms of an enzyme, each having the same mechanism but with differing chemical, physical, or immunologically characteristics. (12 Dec 1998) |
| isoepoxydon dehydrogenase | <enzyme> Interconversion between phyllostine (2-hydroxymethyl-5,6-epoxy-1,4-benzoquinone) and isoepoxydon (4-hydroxy-5,6-epoxycyclohex-2-en-1-one Registry number: EC 1.- (26 Jun 1999) |
| isoerythrolysis | Destruction of erythrocytes by isoantibodies. Origin: iso-+ erythrocyte = G. Lysis, dissolution (05 Mar 2000) |
| isoetharine | <chemical> Adrenergic beta-2 agonist used as bronchodilator for emphysema, bronchitis and asthma. Pharmacological action: adrenergic beta-agonists, bronchodilator agents, sympathomimetic. Chemical name: 1,2-Benzenediol, 4-(1-hydroxy-2-((1-methylethyl)amino)butyl)- (12 Dec 1998) |
| isoflavone 7-O-glucoside-6''-malonate malonylesterase | <enzyme> From roots of chickpea (cicer arietenum) Registry number: EC 3.1.1.- Synonym: ifgmm esterase (26 Jun 1999) |
| isoflavone synthase | <enzyme> Microsomal enzyme from soybeans; converts (2s)-naringenin to genistein and converts (2s)-5,4'-dihydroxflavanone to daidzein; requires NADPH and oxygen; may be a cytochrome p-450-dependent monooxygenase Registry number: EC 1.14.13.- Synonym: genistein synthase, naringenin monooxygenase, NADPH-2'-hydroxydaidzein oxidoreductase (26 Jun 1999) |
| isoflavone-5-O-methyltransferase | <enzyme> Yellow lupin root enzyme catalyses position-specific methylation of the 5-hydroxyl group of a number of isoflavones, has little or no activity with flavones, flavonols, coumarins or phenylpropanoids Registry number: EC 2.1.1.- Synonym: isf-methyltransferase (26 Jun 1999) |
| isoflavones | 3-phenylchromones. Isomeric form of flavones in which the benzene group is attached to the 3 position of the benzopyran ring instead of the 2 position. (12 Dec 1998) |
| isofluorphate | [(CH3)2CH-O]2P(O)F;a toxic cholinergic agent that acts by irreversible inhibition of cholinesterase; an ophthalmic cholinergic agent; also used in biochemical research as an enzyme inhibitor. Synonym: diisopropyl fluorophosphate. (05 Mar 2000) |