Purification of monoclonal antibodies from ascitic fluid using preparative electrophoresis.

Four monoclonal antibodies (including Ig subclasses, G1, G2a, and G2b) were purified from murine ascitic fluid by a preparative electrophoresis system using a charge- and size-based strategy. Most of the smaller contaminating proteins were removed at pH 8.3 when the ascitic fluid was passed through a cartridge containing a separating membrane with a pore size of M(r) 100,000. After this single step, the immunoglobulin heavy and light chains were the only significant bands present when analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A second step, involving electrophoresis at pH 6.4-7.5 depending on the antibody can be used to remove residual contaminants. For each of the antibodies tested, the recovery of activity at each step was over 80%. As this technology is directly scalable, purification of antibodies by the method described here could be considered a cost effective alternative to protein A chromatography.

Identification of species of fish by gradient-gel electrophoresis.

An electrophoretic method is described for distinguishing between fish fillets according to their protein composition. Thaw fluid (4 microL) was applied to one of 14 sample positions of a precast gel, containing a gradient of polyacrylamide of either 2.5 to 27% or 3 to 40%. All reagents and gels are commercially available in ready-to-use form. Either gel provided a distinction between any of the 42 fish types, but the 3 to 40% gel gave better identification because of its superior molecular-sieving properties. Reproducible electrophoretic patterns were obtained for different samples of the same fish type, but small differences were shown for fish of widely different origin, for example Australian and New Zealand ling.

A rapid (less than 10 minute) electrophoresis method for identification of wheat varieties.

Conventional procedures for electrophoretic identification of grain samples according to variety are too slow to permit checking at the time of delivery. The method described permits electrophoretic identification within an hour. It involves extraction of gliadin proteins from crushed grain with 6% urea solution or ethylene glycol, cathodic electrophoresis for 9 min at 300 V in a Micrograd gel (MG 315 from Gradipore Ltd, Sydney, Australia) using sodium lactate buffer (pH 3.1), and staining in Gradipore (at about 50 degrees C). Distinction between a set of Australian varieties was similar to that obtainable with the Australian Standard Procedure.