Analysis of glutathione S-transferase from human liver by isoelectric focusing in a urea minigel system

A method for the rapid analysis of isozyme subunits of glutathione transferase (GST) from human liver is described. Following purification of enzyme protein to electrophoretic homogeneity on columns of GSH-agarose, pooled transferase fractions were concentrated by ultrafiltration and subjected to further fractionation and analysis by urea-isoelectric focusing in minigels using a Hoefer Mighty Small II electrophoresis system. These methods combined with immunoblotting techniques permitted the resolution, detection, and eventual analysis of up to six different subunits of the alpha isozyme of human GST and at least three to four different forms of the pi isozyme of the transferase rapidity, accuracy, and sensitivity of the methodology may prove useful to the analysis and quantification of GST subunits in biopsies of malignant human tissue and to the development of effective chemotherapeutic regimens.