Immobilised metal-ion affinity chromatography purification of histidine-tagged recombinant proteins: a wash step with a low concentration of EDTA

Immobilised metal-ion affinity chromatography (IMAC) is widely used for the purification of recombinant proteins in which a poly-histidine tag is intr oduced. However, other proteins may also bind to IMAC columns. We describe the use of a washing buffer with a low concentration of EDTA (0.5 mM) for t he removal of proteins without histidine tag from IMAC columns. Four histid ine-tagged recombinant proteins/protein complexes were purified to homogene ity from cell culture medium of insect cells by using an EDTA washing buffe r. The presence of a low concentration of EDTA in washing buffers during IM AC may have a general application in the purification of histidine-tagged p roteins. (C) 2001 Elsevier Science B.V. All rights reserved.