title: Examination of the binding behaviour of several proteins with the immobilized copper(II) complexes of o-, m- and p-xylylene bridged bis(1,4,7-triazacyclononane) macrocycles.
abstract: Three new IMAC chelating systems, incorporating immobilised xylenyl-bridged bis(1,4,7-triaza-cyclonane) ligands, complexed with Cu(2+) ions to form binuclear species, have been prepared. Their binding properties have been investigated with three small globular proteins (hen egg white lysozyme, horse skeletal muscle myoglobin and horse heart cytochrome c). The effects of buffer pH, ionic strength and composition on the binding behaviour of these proteins to these new IMAC sorbents have been examined and compared with those found for the corresponding immobilized mononuclear copper complex of 1,4,7-triazacyclononane (tacn). Higher protein binding affinities were observed with the Cu(2+)-bis(tacn) sorbents compared to the Cu(2+)-tacn system, consistent with the immobilized binuclear copper(II) species undergoing enhanced coordinative interaction with the surface-exposed histidine residues of these proteins. Moreover, the protein binding characteristics of these IMAC sorbents at higher ionic strengths, such as 1M NaCl, also reflect the presence of the aromatic ring in the bis(tacn) ligands, whereby hydrophobic pi/pi stacking interactions can occur with the proteins.
authors.affiliation: School of Chemistry, Monash University, Victoria 3800, Australia.
authors.forename: Bim
authors.initials: B
authors.lastname: Graham
authors.forename: Leone
authors.initials: L
authors.lastname: Spiccia
authors.forename: Milton T W
authors.initials: MT
authors.lastname: Hearn
mesh_terms: D000327:Adsorption; D002021:Buffers; D003300:Copper / Q000737:chemistry*; D045304:Cytochromes c / Q000737:chemistry / Q000378:metabolism*; D047028:Macrocyclic Compounds / Q000737:chemistry*; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D014992:Xylenes / Q000737:chemistry*
chemical_list: D002021:Buffers; D047028:Macrocyclic Compounds; D014992:Xylenes; D003300:Copper; D045304:Cytochromes c; D009113:Muramidase