Binuclear Copper(II) Complexes of Bis(1,4,7-triazacyclononane) Ligands Containing Tri- and Tetramethylene Bridging Groups. An Equilibrium and Structural Study

Separation of hexahistidine fusion proteins with immobilized metal ion affinity chromatographic (IMAC) sorbents derived from MN+‐tacn and its derivatives

“…These results are consistent (Haidar et al, 1997;Zanello et al, 1987;Zhang et al, 1995) with the coordination and structural properties of the free M nþ -tacn, M nþ -dtne and M nþ -dtnp complexes as determined from X-ray crystallographic and other spectroscopic methods. Moreover, these trends follow the known binding behavior of Ndonor groups, such as the nitrogen lone pair electrons of the imidazole moiety of histidine residues, which show a high propensity for coordinative interactions with Cu 2þ -or Ni 2þ ions.…”

“…Compared to other tri-or tetradentating chelating ligands, tacn and its derivatives have much larger stability constants for many borderline metal ions, with values typically higher than IDA by at least 4-10 orders of magnitude, that is, in the range of 16 log b 30 (Haidar et al, 1997;Spiccia et al, 1997;Tanaka et al, 1977;Zhang et al, 1995). The homologues, bis(1,4,7-triazacyclononyl) ethane (dtne) and bis(1,4,7-triazacyclononyl)propane (dtnp), involve two tacn macrocyclic rings linked via either an ethyl or a propyl bridge respectively (Fig.…”

Comparison of the binding behavior of several histidine-containing proteins with immobilized copper(II) complexes of 1,4,7-triazacyclononane and 1,4-bis(1,4,7-triazacyclononan-1-yl)butane

“…By introducing the added dimension of proximal metal ion centres to the IMAC adsorption process, we were interested to examine the potential of such binucleating ligand systems to expand the available selectivity options. The tacn 2 butane ligand was considered an suitable candidate for this purpose since (i) it possesses secondary amine groups which can be utilized to attach the ligands onto a support material, (ii) it forms a highly stable binuclear copper(II) complex, whereby the two tacn macrocycles can bind to separate Cu 2+ ions [12,13], and (iii) the resulting complex is "coordinatively unsaturated" in the sense that ligand exchange processes [14] can still occur with more strongly binding, electron-donating groups present on the surface of protein(s).…”

Changed loading conditions and lysate composition improve the purity of tagged recombinant proteins with tacn‐based IMAC adsorbents

“…Tacn and dtnp were synthesized as previously described [11,12,18,19]. The procedures employed to immobilize these ligands onto epoxy-activated Sepharose™ 6 FF are described in the Supporting information.…”

“…1) and their numerous analogs have even higher metal ion stability constants (i.e. with β ≥ 10 10 -10 18 ) [10][11][12]. Tacn-based ligands exhibit very low toxicity indices and can be easily immobilized onto support materials via oxirane or other chemistries [13][14][15][16].…”