Immobilized metal-ion affinity chromatography: imidazole proton pump and chromatographic sequelae. II. Chromatographic sequelae.

Isocratic elution with imidazole of some protein models from a chelating gel, CSFF-IDA-M(II), resulted in their desorption owing to the low pH(6-->4) of the mobile, phase rather than to the imidazole itself (imidazole-generated fall in pH; proton pump). Gradient elution with imidazole was best accomplished when the chelating gel was initially converted into its imidazole complex, CSFF-IDA-M(II)Im. The exploitation of the imidazole-generated proton pump in the IMAC of proteins may enhance the versatility of this type of chromatography.