Denaturing Gradient Gel Electrophoresis DGGE or TGGE

DGGE analysis also relies on differential electrophoretic migration of wild-type and mutant DNA to detect sequence differences.62,63 Double-stranded DNA molecules differing by a single base substitution exhibit different electrophoretic mobilities compared to homodimers migrating through a gel containing a gradient of increasing concentration of denaturing agent. Detection is by nonradio-active means. When the appropriate primers are used and optimal conditions are attained, DGGE is rapid and highly reliable. This technique is capable of close to 100% accuracy in PCR products up to 1000 base pairs long.52 Although this method is rapid, it is costly for small numbers of samples because of the requirement for guanosine-cytosine (GC) clamps.

A refinement of this method (TGGE) replaces the chemical denaturing gradient of DNA in DGGE with temperature as the denaturant.64

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