Single-step purification of recombinant green fluorescent protein on expanded beds of immobilized metal affinity chromatography media

Immobilized metal ion affinity chromatography (IMAC) in expanded bed mode is used for purifying recombinant green fluorescent protein (GFP) overexpressed in Escherichia coli. The purification is carried out on two different matrices, i.e. Ni2+ Streamline™ and Ni2+ cross-linked alginate beads. The binding isotherms to both IMAC media followed the Langmuir model. The maximum binding capacity (qmax) of Ni2+ Streamline™ and Ni2+ cross-linked alginate for the GFP was 1,42,860 FU ml−1 and 18,000 FU ml−1, respectively. The expanded bed column chromatography using Ni2+ Streamline™ gave 2.7-fold purification with 89% of GFP recovery, while Ni2+ alginate gave 3.1-fold purification with 91% of GFP recovery. SDS-PAGE of purified GFP in both cases showed single band. The results obtained in the expanded bed chromatography are compared with those obtained in packed bed chromatography.