| centrifugation, density gradient | Separation of particles according to density by employing a gradient of varying densities. at equilibrium each particle settles in the gradient at a point equal to its density. (12 Dec 1998) |
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| density gradient | <chemistry> A column of liquid in which the density varies continually with position, usually as a consequence of variation of concentration of a solute. Such gradients may be established by progressive mixing of solutions of different density as for example: sucrose gradients) or by centrifuge induced redistribution of solute (as for caesium chloride gradients). Density gradients are widely used for centrifugal and gravity induced separations of cells, organelles and macromolecules. The separations may exploit density differences between particles or primarily differences in size, in which latter case the function of the gradient is chiefly to stabilise the liquid column against mixing. (12 Jan 1998) |
| density gradient centrifugation | <technique> High-speed centrifugation inwhich molecules float at a point wheretheir density equals that in a gradient of cesium chloride or sucrose. (12 Jan 1998) |
| sucrose | Nonreducing disaccharide, _ D glucopyranosyl _ D fructofuranose. (18 Nov 1997) |
| sucrose alpha-d-glucohydrolase | <enzyme> An enzyme hydrolyzing sucrose and maltose; in a complex with isomaltase; hence, hydrolyzes both sucrose and isomaltose; found in the intestinal mucosa; a deficiency of this enzyme results in defective digestion of sucrose and linear a1,4-glucans. Synonym: sucrase. (05 Mar 2000) |
| sucrose - fructan 6-fructosyltransferase | <enzyme> Catalyses the formation and extension of beta-2,6-linked fructans, typical of grasses; from barley, hordeum vulgare; genbank x83233 Registry number: EC 2.4.1.- Synonym: barley 6-sft (26 Jun 1999) |
| sucrose haemolysis test | Isotonic sucrose promotes binding of complement to red blood cells; in paroxysmal nocturnal haemoglobinuria a proportion of the cells is sensitive to complement-mediated lysis, and haemolysis ensues. (05 Mar 2000) |
| sucrose permease | <chemical> Sucrose-utilizing enzyme Chemical name: permease, sucrose (26 Jun 1999) |
| sucrose-phosphate synthase phosphatase | <enzyme> A type 2a phosphoprotein phosphatase Registry number: EC 3.1.3.- Synonym: sps-phosphatase (26 Jun 1999) |
| sucrose synthase | <enzyme> Sus1 gene product isolated from maise Registry number: EC 2.4.1.13 Synonym: sucrose synthetase, udp-glucose-d-fructose-2-glycosyltransferase, suc synthase 1, suc synthase1, sus1 gene product (26 Jun 1999) |
| dietary sucrose | Sucrose present in the diet. It is added to food and drinks as a sweetener. (12 Dec 1998) |
| atrioventricular gradient | The diastolic pressure difference between the atrium and ventricle. (05 Mar 2000) |
| magnetic field gradient | In magnetic resonance imaging, a magnetic field that varies with location, superimposed on the uniform field of the magnet, to alter the resonant frequency of nuclei and allow recovery of their spatial position. Synonym: field gradient. (05 Mar 2000) |
| ventricular gradient | The algebraic sum of (i.e., the net electrical difference between) the area enclosed within the QRS complex and that within the T wave in the electrocardiogram. (05 Mar 2000) |
| voltage gradient | <physiology> Literally, the electric field in a region, defined as the potential difference between two points divided by the distance between them. Used more loosely, the potential difference across a plasma membrane. (18 Nov 1997) |