A laboratory demonstration illustrating bioseparations using colorful proteins

A simple in class laboratory illustrating the principles of ion exchange chromatography as a bioseparation technique is described. A protein's isoelectric point as a driving force for ion exchange chromatography is easily demonstrated by using combinations of proteins with natural color or fluorescence, such as DsRed2, enhanced green fluorescent protein (EGFP), and flavodoxin. Simple equipment is required for this separation which can be performed on a desk top. The experiment can stimulate a range of discussion about process parameters that would create a more efficient separation of the proteins, other types of chromatography, and bioseparations in general.