Purification of the i-antigen 51A fromParamecium tetraurelia by immunoaffinity chromatography

Purification of the surface antigen ofParamecium tetraurelia (termed i-antigen) by previously published procedures has been shown to result in preparations which frequently contain contaminating proteins including a thiol-activated protease. Alternate procedures for the purification of i-antigen were developed using ion-exchange chromatography. While certain of these procedures result in a homogeneous preparation of i-antigen, the poor yields obtained make these procedures impractical. An alternate method for the purification of i-antigen was developed using immunoaffinity chromatography. Purification by this technique proved to be superior to the various standard procedures described previously. The immunoaffinity column is rapid and results in a recovery, on the average, of over 95% of the applied material. The columns are readily regenerated and may be used numerous times without loss of capacity or purification ability. The i-antigen purified by this method appears homogeneous immunologically and electrophoretically on polyacrylamide gel electrophoresis and isoelectric focusing.