Purification of the variant antigens of Trypanosoma congolense: a new approach to the isolation of glycoproteins.

We describe a new and rapid method for the isolation and purification of the variant antigens of Trypanosoma congolense. The procedure consists of (a) partial lysis of trypanosomes with dioxane, (b) lectin-affinity-chromatography with Con A-Sepharose, (c) electrophoretic desorption and concomitant separation of Con A-Sepharose-bound glycoproteins in a granulated electrofocusing gel, (d) electrophoretic elution of focused proteins from the granulated gel particles. The efficiency of each step was followed quantitatively by affinity electrophoresis. 73% of the variant antigens originally present in a trypanosomal lysate could be recovered. From 10(10) trypanosomes 2 mg of pure variant antigen were obtained. The variant antigen of the trypanosome clone used exhibits heterogeneity in molecular weight as well as in electric charge.