TWO DIMENSIONAL ELECTROPHORESIS (2DE) is one of the best experimental tools for the reliable separation of thousands of proteins in a single gel. 2DE consists of a tandem pair of electrophoretic separations:

• In the first dimension, proteins are resolved in according to their isoelectric points (pIs) using immobilized pH gradient electrophoresis (IPGE), isoelectric focusing (IEF), or non-equilibrium pH gradient electrophoresis (NEPHGE). Under standard conditions of temperature and urea concentration, the observed focusing points of the great majority of proteins using IPGE (and to a lesser extent IEF) closely approximate the predicted isoelectric points calculated from the proteins' amino acid compositions (Ref. 15, Ref. 16).

• In the second dimension, proteins are separated according to their approximate molecular weight using sodium dodecyl sulfate poly-acrylamide-electrophoresis (SDS-PAGE). This technique can provide molecular weight approximations (+/- 10%) for most proteins, with some dramatic exceptions.

Details of 2D electrophoretic techniques are available elsewhere online:

1. from the SWISS-2DPAGE team at the ExPASy Molecular Biology Server ( http://www.expasy.ch/ch2d/technical-info.html),
2. from the Danish Center for Human Genome Research ( http://biosun.biobase.dk/~pdi/procedures/procedure.html), and
3. from the Large Scale Biology Corporation (http://www.lsbc.com:80/isodalt/index.htm).

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$Date: 1999/01/18 21:24:31 $ /
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