Electrophoresis of duplex deoxyribonucleic acid in multiple-concentration agarose gels: fractionation of molecules with molecular weights between 2 .times. 106 and 110 .times. 106

By use of multiple-concentration agarose gels, the distance migrated by linear, duplex DNA during agarose gel electrophoresis has been measured as a function of agarose concentration (A) and molecular weight of the DNA (Mr) for molecules with an Mr between 1.88 X 10(6) and 110 X 10(6). Conditions for obtaining a linear plot of log Mr as a function of distance migrated (D) have been found for DNA molecules with an Mr between 5.47 X 10(6) and 110 X 10(6); improved conditions for fractionating such molecules are described. The ratio of the D of a DNA with an Mr of 26.5 X 10(6) to the D of a DNA with an Mr of 77 X 10(6) was plotted as a function of A and electrical field (E). By use of A values between 0.075 and 0.70% and a constant E, this plot had a single maximum. The maximal value of the above ratio was a decreasing function of E, and the A at this maximal value was also a decreasing function of E.