10.3.5 Two-dimensional polyacrylamide gel electrophoresis
This technique combines the technique of IEF (first dimension), which separates
proteins in a mixture according to charge (pI), with the size separation technique
of SDS–PAGE (second dimension). The combination of these two techniques to give
two-dimensional (2-D) PAGE provides a highly sophisticated analytical method for
analysing protein mixtures. To maximise separation, most workers use large format123 45
Fig. 10.8A typical isoelectric focussing gel. Track 1 contains a mixture of standard proteins of known
isoelectric points. Tracks 2–5 show increasing loadings of venom from the Japanese water moccasin snake.
(Courtesy of Bio-Rad Laboratories Ltd.)414 Electrophoretic techniques