Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Patent
1989-10-02
1991-09-10
Niebling, John F.
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
2041801, 2041828, B65D 8518, B65D 7500
Patent
active
050471368
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to the area of electrophoretic separation and analysis of biopolymers, and more specifically to apparatuses for electrophoretic separation of molecular weight DNA in a gel.
PRIOR ART
Separation of mixtures of biopolymers, in particular those whose size exceeds 5.10.sup.4 pairs of nucleic bases, is based on pulse electrophoresis, comprising successive generation of crossed electric fields in the gel with the mixture of molecular weigh DNA.
Known in the art is an apparatus for separating a mixture of DNA molecules (G. F. Carle, M. Frank and M. V. Olson. Electrophoretic Separation of Large DNA Molecules by Periodic Inversion of the Electric Field.--Science, v. 232, 1986, pp. 65-68), wherein the rectangular electrophoresis chamber is fitted with two opposite linear electrodes positioned horizontally, between which the gel unit is placed. The voltage from a power supply is applied to the electrodes via a switch, so that during 3/4 of the time interval selected the electrodes are under a direct voltage and 1/4 of this time interval--under a reverse voltage, this cycle repeated many times. This causes the direction of DNA molecule movement to vary periodically by 180.degree.. Such an angle is not optimal for a wide range of molecular masses of DNA molecules being separated and consequently individual fractions with size above 2.10.sup.6 nucleic base pairs (NBP) cannot be separated in this known apparatus. Furthermore, reciprocal movement of the molecules in the gel unit results in a longer time to separate the initial mixture, i.e. to lower productivity of the apparatus.
Also known in the art is an apparatus (G. Chy, D. Vollrath, R. W. Davis, Separation of Large DNA Molecules by Contour=Clamped Homogeneous Electric Fields, Science, v. 234, 1986, pp. 1582-1585), wherein six groups of point electrodes, positioned vertically relative to the gel unit, form a hexahedron, electrically looped via identical resistors, enclosing the gel unit. The voltage from a power supply is alternately applied via a switch to two pairs of oppositely positioned electrode groups. A third pair of electrodes is passive and serves to generate a uniform electric field between electrodes. In this arrangement DNA molecules move with a change in direction by 120.degree. each voltage switching clock interval. At the same chamber size as in the previously cited apparatus, the gel unit has to be smaller and consequently carry a smaller number of deposited samples, this is also impaiiring the productivity of the apparatus. Furthermore, the power of the power supply has to be doubled because the current through the electrodes has to be not lower than through the buffer solution coating the gel unit.
Known in the art is an apparatus for separating high molecular weight DNA in a gel (U.S. Pat. No. 4,473,452) allowing separation of DNA molecules with sized ranging from 5.10.sup.4 to 9.10.sup.6 NBP. Its square electrophoretic chamber is fitted with four groups of electrodes, with two adjacent chamber walls mounting groups of point electrodes electrically connected to each other within a group, and the other two adjacent walls mounting two individual point electrodes in the immediate vicinity from the ends of two opposite to them electrode groups. The voltage from a power supply is applied via a switch to the electrodes, with voltage of negative polarity applied to the group of electrodes and with voltage of positive polarity applied to the opposing individual electrode for a certain time interval, then the voltage is switched to the second group of electrodes and second individual electrode for the same time interval and in the same polarity arrangement. This causes crossed curvilinear electric fields in the gel unit positioned inside this chamber, causing DNA molecules to move along complex paths, the direction whereof varies from 90.degree. to 180.degree. as the molecule approaches the point electrodes.
Curvature of the fields generated in this known apparatus results, firstly, in curvilear tracks of i
REFERENCES:
patent: 4473452 (1984-09-01), Cantor et al.
Chu, Vollrath, Davis, Separation of Lg. DNA Molecules by Contour-Clamped Homogeneous Electric Fields, Science, vol. 234, 1986, pp. 1582-1585.
Beritashvili David R.
Karklit Lev V.
Tverdokhlebov Evgeny N.
Koestner Caroline
Niebling John F.
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