Taxonomy of Finfish (1+2)

6.2.4 Support media

6.2.4 Supporting Media

A variety of anti-convection media are being used in zone electrophoresis. They exhibit several properties. An ideal medium should have the following features: -

Chemical nature inert

Availability easy

Electrical conductivity high

Adsorptivity low

Sieving effect desirable

Porosity controlled

Transparency high

Electro-endosmosis (EEO) low

Rigidity moderate to high

Preservation feasible

Toxicity low

Preparation easy

The original material, filter paper, has now been replaced by a variety of gels. Cellulose acetate and agar have large pore size and are used for separation of large protein molecules and for immunodiffusion. Starch and polyacrylamide have a pore size to the molecular size of many proteins, so there is also a molecular sieving effect. The pore size of acrylamide gels is adjustable. Protein resolution depends on the pH and ionic strength of the buffer, the pore size of the gel and the current applied. Buffer pH is usually 8 to 9 ensuring that all proteins are negatively charged and migrate to anode. Heat is produced in proportion to the product of Volt x Ampere so temperature must be controlled by using cooling devices. The details of various media are discussed below.