DISPERSION COEFFICIENTS OF LAMBDA-DNA IN AGAROSE GELS DURING ELECTROPHORESIS BY FRINGE RECOVERY AFTER PHOTOBLEACHING

By combining an electrophoretic cell with a fringe recovery after phot obleaching setup, we have measured both the electrophoretic mobility m u and the dispersion coefficient D of double-stranded lambda-DNA in ag arose gel as a function of the applied electric field E. Besides the d etermination of the mobilities, the analysis of the exponential decay of the signal gives, for the first time, experimental values of the lo ngitudinal D-x and transverse D-y dispersion coefficients (field E per pendicular and parallel to the light fringes, respectively). Time disp ersion measurements are complicated by the existence of a bleached are a drift time. We present an analysis of their different contributions. Both dispersion coefficients increase linearly with increasing field E and, in the range of field we used, D-x is larger than D-y. Our resu lts are consistent with the recent theoretical predictions of Slater ( Electrophoresis 1993, 14, 1-7) and Duke et al. (Biopolymers 1994, 94, 239-247).