Chelate imidazole-containing

Hydrogenated products of the pyrazoles and the imidazoles, i.e. the pyrazolines and imidazolines, have some importance as ligands, but have seldom been reported. Only some chelate ligands containing imidazoline have been studied in some detail and will be discussed in Section 13.2.5.3. 

Separations with imidazole-containing copolymers have been used for the purification of proteins containing natural metal-ion binding sites and His-tag recombinant proteins, which bind to the metal immobilised onto the metal chelating group (Galaev et al, 1997 Kumar et al, 2003 Mattiasson c/ 7,2007). 

Leonhardt et al were able to show a specific hydrolytic effect when treating nitrophenyl esters with an MIP imprinted with pyridine derivatives of N-boc-amino acids using DVB and 4(5)-vinylimidazole as monomers in combination with chelated Co ions. Compared to the control polymer, hydrolysis was accelerated by a factor of 4 to 5, while a comparison with MIP imprinted with other pyridine derivatives of N-boc-amino acids only gave an acceleration of the reaction by a factor of 2 to 3. Robinson et al used phosphonates as TSA and showed a catalytic effect of an MIP imprinted with p-nitrophenylmethyl phosphonate, using 4(5)-vinylimidazole and Co ions, on the hydrolysis of p-nitrophenol acetate. The authors— aware of the fact that imidazole containing polymers in general exhibit catalytic effects—could nevertheless demonstrate that the imprinted specimens were of 60% higher activity than the control polymers. 

Ferric ion was immobilized on a Chelating Sepharose Fast Flow column preparatory to the separation of seven enkephalin-related phosphopep-tides.17 Non-phosphorylated peptides flowed through the column, and the bound fraction contained the product. The capacity of the column was found to be 23 pmol/mL by frontal elution analysis. Cupric ion was immobilized on Chelating Superose for the isolation of bovine serum albumin.18 Cupric ion was immobilized on a Pharmacia HiTrap column for the separation of Protein C from prothrombin, a separation that was used to model the subsequent apparently successful separation of Factor IX from prothrombin Factor IX activity of the eluate was, however, not checked.19 Imidazole was used as the displacement agent to recover p-galactosidase from unclarified homogenates injected onto a nickel-loaded IMAC column.20 Pretreatment with nucleases and cleaning in place between injections were required procedures. A sixfold purification factor was observed. 

Template Polymers. Template effects in chelating polymers constitute an interesting development in the field of metal containing polymers. The Template effects are interpreted by the fact that the small molecule is templating a pattern in the macromolecule which can be recognized by the same molecule in a subsequent process. The idea is to prepare a polymer from the metal-chelated monomer, to remove the metal ion, and then to measure the selectivity of the prepared polymer for the metal ion of the template [36]. Typical examples of template systems are 4-vinyl-4 -methylbipyridine (Neckers [36]) and 1-vinyl-imidazole (Tsuchida [37]). These are polymerized in presence of divinylbenzene [36] and appropriate metal salts (Co2+, Cu2+, Ni2+, Zn2+). The template metal ions are removed by acid leaching and the polymer subsequently used for metal ion absorption studies (Fig. 16). 

Complexes of the stoichiometry [ML3] [C104]2 [L = thiabendazole (65)] contain the metal in an octahedral coordination with the chelating ligand coordinated via the nitrogens of the imidazole and thiazole rings.465... 

Schiff base complexes formed from the tridentate amino acids are ambidentate in nature. Thus, with histidine, only pyruvate of those mentioned above leads to the His binding through the N(amino) and N-3(imidazole) with the others glycine-like chelation occurs. These different modes can be readily distinguished by their CD spectra. There appears to have been only a limited number of studies on the S-containing amino acids.45 7... 

Absorbent STREAMLINE Chelating, saturated with NiS04 and equilibrated in 20 mM Tris, pH 8.0 containing 0.5 M NaCl and 5 mM imidazole. (The protein is expressed with His-tag). 

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