ABSTRACT
Electrophoretic separation of DNA fragments, such as PCR products, is usually accomplished in agarose, polyacrylamide, or composite agarose-polyacrylamide gels [7]. At slightly basic separation conditions (7 pH 9), DNA molecules are negatively charged, so they should be loaded at the cathode end of the separation platform and migrate toward the anode when the electric field is applied. Under denaturing conditions the electrophoretic mobility of DNA fragments is primarily determined by their size, while under nondenaturing separation conditions it is also influenced by the sequence-dependent secondary structure [8]. Agarose gels are usually employed to analyze double-stranded DNA molecules in size from hundreds of base pairs (bp) to tens of thousands of base pairs, and polyacrylamide gels are regularly used for high-resolution DNA fragment analysis from several base pairs up to 1000 bp.
