Immobilized metal-ion affinity chromatography (IMAC) is suitable for the purification of proteins under denaturing conditions.  Either guanidine-HCl or urea can be used, although guanidine-HCl is a stronger denaturant than urea.  Proteins that have been adsorbed to the column in the presence of guanidine-binding buffer may be washed with urea-binding buffer and eluted with urea elution buffer.

Protocol: Purification of Histidine-Tagged Proteins under Denaturing Conditions Using IMAC Protocol