Analysis of the inversion effect in pulsed field gel electrophoresis by a two-dimensional contour-clamped homogeneous electric field system.

A two-dimensional contour-clamped homogeneous electric field electrophoresis was used for the separation of the yeast Saccharomyces cerevisiae chromosomes. The role of different pulse times and field strengths was examined. The resulting complex migration curves were similar to those predicted by the bag model. They are characterized by a straight line in the region of lower molecular weight where the migration is inversely proportional to the molecular weight and a mobility inversion in the region of higher molecular weight both depending on the conditions chosen for the two directions. The quantitative analysis of the data was compared with the predictions of the bag model which is shown to be a good approximation. Using this experimental approach the separation pattern of a commercially available S. cerevisiae standard was examined under standard electrophoresis conditions, and chromosomes IV and XII were found to be inverted.