Temperature gradient gel electrophoresis

[1][2][3] The same equipment can be used for analysis of protein, which was first done by Thomas E. Creighton of the MRC Laboratory of Molecular Biology, Cambridge, England.

As the temperature is increased, the strands begin to separate (melting), and the speed at which they move through the gel decreases drastically.

Critically, the temperature at which melting occurs depends on the sequence (GC basepairs are more stable than AT due to stacking interactions, not due to the difference in hydrogen bonds [citation needed] (there are three hydrogen bonds between a cytosine and guanine base pair, but only two between adenine and thymine), so TGGE provides a "sequence dependent, size independent method" for separating DNA molecules.

As a result of this melting, the DNA spreads through the gel and can be analyzed for single components, even those as small as 200-700 base pairs.

Discrete portions or domains of the fragment suddenly become single-stranded within a very narrow range of denaturing conditions" (Helms, 1990).

There are a number of disadvantages to this technique: "Chemical gradients such as those used in DGGE are not as reproducible, are difficult to establish and often do not completely resolve heteroduplexes" (Westburg, 2001).

To separate nucleic acids by TGGE, the following steps must be performed: preparing and pouring the gels, electrophoresis, staining, and elution of DNA.

[6] Depending on which type of TGGE is to be run, either perpendicular or parallel, varying amounts of sample need to be prepared and loaded.

According to a recent investigation by Wong, Liang, Kwon, Bai, Alper and Gropman,[7] TGGE can be utilized to examine the mitochondrial DNA of an individual.

DGGE of small ribosomal subunit coding genes was first described by Gerard Muyzer,[9] while he was Post-doc at Leiden University, and has become a widely used technique in microbial ecology.

For instance, Tabatabaei et al. (2009) applied DGGE and managed to reveal the microbial pattern during the anaerobic fermentation of palm oil mill effluent (POME) for the first time.