Separation of DNA restriction fragments by high performance capillary electrophoresis with low and zero crosslinked polyacrylamide using continuous and pulsed electric fields

This paper presents results on the separation of DNA restriction fragments by high performance capillary electrophoresis (HPCE). Capillaries containing polyacryl- amide with low amounts of crosslinking agent (i.e. 0.5% C) were first studied. The greater molecular accessibility offered with columns of low crosslinking, relative to higher crosslinked gels (e.g. 5%C), permitted high efficiency separations of double stranded DNA fragments up to 12 000 base pairs in length. Capillaries containing no crosslinking agent, i.e. linear polyacrylamide, were then examined. Ferguson plots (i.e. log mobility vs. %T) were used to assess the size selectivity of linear polyacryl- amide capillaries. In another study, it was determined that the relative migration of DNA species was a strong function of applied electric field and molecular size. Lower fields yielded better resolution than higher fields for DNA molecules larger than about 1000 base pairs, albeit at the expense of longer separation time. Based on these results, we have examined pulsed field HPCE and have demonstrated the use of this approach to enhance separation.