Purification of a lectin from Canavalia ensiformis using PEG–citrate aqueous two-phase system

A PEG/citrate aqueous two-phase system was tested in the partition of commercial Concanavalin A (Con A) and subsequently applied to the extraction and purification of Con A from the crude extract of Canavalia ensiformis seeds. Con A was successfully extracted to the bottom phase of a system composed of 22% (w/w) PEG8000 and 12% (w/w) citrate at pH 6.0. The obtained purification factor was 11.5 without any loss in the hemagglutinating activity. The purity of extracted lectin was confirmed by SDS-PAGE analysis.