One bed volume metal salt solution is sufficient. Elution can occur by displacement of the protein with a competitive molecule or by changing the pH value. In the first case, the component added to the buffer displaces the protein from the column in corresponding concentration. When lowering the pH value in the buffer the binding affinity of the complex protein-metal ion is reduced and the protein can be desorbed. 1 M NaCl to which 1 mM imidazole was added.
Elution can take place either with a linear imidazole gradient or with step gradients.
Alternatively, bound proteins can be eluted from the column using a descending pH gradient. Regeneration For the regeneration of the metal chelate columns approx.