Immobilized metal ion affinity partitioning of cells in aqueous two-phase systems: erythrocytes as a model

Immobilized metal ion affinity partitioning of erythrocytes from different species is described. We have explored the affinity between transition metal chelates and metal-binding sites situated on the cell surface by partitioning in aqueous two-phase system composed of poly(ethylene glycol) and dextran. Soluble metal-chelate-poly(ethylene glycol) was prepared by fixing metal ions to poly(ethylene glycol) via the covalently bonded chelator, iminodiacetic acid. The partitioning behaviour of erythrocytes in systems at different concentrations of the ligand was tested. The copper-chelate-poly(ethylene glycol) was quite effective in the affinity extraction of human and rabbit erythrocytes, while the zinc-chelate-poly(ethylene glycol) displayed significant affinity only to the rabbit cells. Furthermore, the influence of various effectors such as imidazole, sialic acid on immobilized metal ion affinity partitioning of erythrocytes was examined.