Immobilized metal affinity chromatography and human serum proteomics

Metal-binding proteins have a pivotal role in normal and diseased states. We used metal affinity chromatography to enrich a fraction of human serum proteins on immobilized columns loaded with cadmium, nickel, zinc, copper, or lead in bis–Tris saline and these proteins were identified using LC–MS/MS. Tens of enriched proteins were identified and we here present the 20 most abundant for binding each metal. The binding of various proteins (complement C3, alpha-2-macroglobulin, serum albumin, apolipoprotein B-100, complement component 4B preproprotein, apolipoprotein A–I, serotransferrin, alpha-1-antitrypsin, ceruloplasmin, 47 kDa protein, uncharacterized protein DKFZp686P15220, transthyretin, hemopexin, inter-alpha-trypsin inhibitor heavy chain H2, and histidine-rich glycoprotein) to different metals using immobilized metal affinity chromatography was compared to the literature. Although many metal-binding properties of these proteins have been confirmed, new metal-binding proteins have also been identified. The metal array use in the proteomic biomarker search technologies gives this data particular importance.