Classification of mouse liver proteins by immobilized metal affinity chromatography and two-dimensional electrophoresis.

Mouse liver proteins were classified into metal-binding and non-binding proteins by combining immobilized metal ion affinity chromatography (IMAC) and two-dimensional electrophoresis (2-DE). The proteins were fractionated by three metal ions, Zn2+, Ni2+ and Cu2+, immobilized on iminodiacetic acid and then separated by 2-DE. The total number of protein spots resolved by 2-DE increased approximately twofold when the proteins were prefractionated by IMAC. By establishing 2-DE standard patterns, 371 proteins were selected and then characterized according to their specificity in binding the three different metal ions. Only 48 proteins did not bind to any of the three metal ions investigated. Cu2+ was the most efficient ion in binding different proteins (310) compared to the other metals. Cu2+ bound to 42 proteins specifically and to 268 proteins unspecifically. Both Zn2+ and Ni2+ showed specific affinity only to four proteins.