| Tiselius electrophoresis cell | The special container in a Tiselius apparatus containing the solution to be analyzed electrophoretically. (05 Mar 2000) |
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| electrophoresis | <technique> Separation of ionic molecules, (principally proteins) by the differential migration through a gel according to the size and ionic charge of the molecules in an electrical field. High resolution techniques normally use a gel support for the fluid phase. Examples of gels used are starch, acrylamide, agarose or mixtures of acrylamide and agarose. Frictional resistance produced by the support causes size, rather than charge alone, to become the major determinant of separation. Smaller molecules with a more negative charge will travel faster and further through the gel toward the anode of an electrophoretic cell when high voltage is applied. Similar molecules will group on the gel. They may be visualised by staining and quantitated, in relative terms, using densitometers which continuously monitor the photometric density of the resulting stain. The electrolyte may be continuous (a single buffer) or discontinuous, where a sample is stacked by means of a buffer discontinuity, before it enters the running gel/ running buffer. The gel may be a single concentration or gradient in which pore size decreases with migration distance. In SDS gel electrophoresis of proteins or electrophoresis of polynucleotides, mobility depends primarily on size and is used to determined molecular weight. In pulse field electrophoresis, two fields are applied alternately at right angles to each other to minimise diffusion mediated spread of large linear polymers. See: electrofocussing, pulse field electrophoresis (01 Dec 1998) |
| electrophoresis, agar gel | Electrophoresis in which agar or agarose gel is used as the diffusion medium. (12 Dec 1998) |
| electrophoresis, capillary | A highly-sensitive (in the picomolar range, which is 10,000-fold more sensitive than conventional electrophoresis) and efficient technique that allows separation of proteins, nucleic acids, and carbohydrates. (12 Dec 1998) |
| electrophoresis, cellulose acetate | Electrophoresis in which cellulose acetate is the diffusion medium. (12 Dec 1998) |
| electrophoresis, disc | Electrophoresis in which discontinuities in both the voltage and pH gradients are introduced by using buffers of different composition and pH in the different parts of the gel column. The term 'disc' was originally used as an abbreviation for 'discontinuous' referring to the buffers employed, and does not have anything to do with the shape of the separated zones. (12 Dec 1998) |
| electrophoresis, gel, pulsed-field | Electrophoresis in which the direction of the electric field is changed periodically. This technique is similar to other electrophoretic methods normally used to separate double-stranded DNA molecules ranging in size up to tens of thousands of base-pairs. However, by alternating the electric field direction one is able to separate DNA molecules up to several million base-pairs in length. (12 Dec 1998) |
| electrophoresis, gel, two-dimensional | Electrophoresis in which a second perpendicular electrophoretic transport is performed on the separate components resulting from the first electrophoresis. This technique is usually performed on polyacrylamide gels. (12 Dec 1998) |
| electrophoresis, paper | Electrophoresis in which paper is used as the diffusion medium. This technique is confined almost entirely to separations of small molecules such as amino acids, peptides, and nucleotides, and relatively high voltages are nearly always used. (12 Dec 1998) |
| electrophoresis, polyacrylamide gel | Electrophoresis in which a polyacrylamide gel is used as the diffusion medium. (12 Dec 1998) |
| electrophoresis, starch gel | Electrophoresis in which a starch gel (a mixture of amylose and amylopectin) is used as the diffusion medium. (12 Dec 1998) |
| two dimensional gel electrophoresis | <technique> A high resolution separation technique in which protein samples are separated by isoelectric focussing in one dimension and then laid on an SDS gel for size determined separation in the second dimension. Can resolve hundreds of components on a single gel. (18 Nov 1997) |
| zone electrophoresis | <chemistry, procedure> A type of electrophoresis used by physical chemists. In it, the components of a mixture are separated into distinct zones by moving the solution through a porous medium such as filter paper. (06 May 1997) |
| free electrophoresis | Electrophoresis of substances placed in a solution in a U-shaped tube. (05 Mar 2000) |
| lipoprotein electrophoresis | Electrophoretic separation of plasma lipoproteins. (05 Mar 2000) |