Rapid assay for the analysis of class III metallothioneins by capillary zone electrophoresis in crude extracts of microalgal cells exposed to cadmium

Abstract

An optimization strategy for the separation and analysis of class III metallothioneins from a complex matrix by capillary zone electrophoresis (CZE) is presented and illustrated. Metallothioneins are a group of polypeptides used for many organisms to alleviate stresses imposed by exposure to heavy-metal excess. The analysis requires several steps: chromatography on exclusion or anion-exchange columns, ultrafiltration and HPLC with derivatization. In the present paper, a rapid and simple separation technique by CZE with an uncoated polyimide-clad fused-silica capillary is described. This technique permits the analysis of these molecules without prior steps of purification and derivatization. The running conditions were voltage −12 kV, room temperature and 150 mM sodium phosphate buffer (pH 3.5). Based on this preliminary study, CZE with an uncoated fused-silica capillary using sodium phosphate buffer appears to be a useful technique for the separation of class III metallothioneins.