potassium-thiocyanate and imidazole

Poly[(N-vinylimidazole)-maleic acid] (poly(VIm-MA)), copolymeric hydrogels were prepared by gamma-irradiating ternary mixtures of N-vinylimidazole-maleic acid-water in a (60)Co-gamma source. Cu(II) and Co(II) ions were chelated within the gels at pH=5.0. The maximum adsorption capacity of the gels were 3.71 mmol/g dry gel for Cu(II) and 1.25 mmol/g dry gel for Co(II) at pH=5.0. The swelling ratios of the gels were 1200% for poly(VIm-MA), 60 and 45% for Cu(II) and Co(II)-chelated poly(VIm-MA) gels at pH=5.0 in acetate buffer solution. These affinity gels with different swelling ratios for plain poly(VIm-MA), Cu(II)-, and Co(II)-chelated poly(VIm-MA), in acetate and phosphate buffers were used in the bovine serum albumin (BSA) adsorption/desorption studies in batch reactor. The maximum BSA adsorption capacities of the gels were 0.38 g/g dry gel for plain, 0.88 g/g dry gel for Cu(II)-chelated poly(VIm-MA) and 1.05 g/g dry gel for Co(II)-chelated poly(VIm-MA) gels. Adsorption capacity of BSA by the gels was reduced dramatically by increasing the ionic strength adjusted with NaCl. More than 95% of BSA were desorbed in 10 h in desorption medium containing 0.1M of EDTA for metal ion-chelated gels at pH=4.7.

Topics: Adsorption; Animals; Cattle; Chelating Agents; Cobalt; Colloids; Copper; Edetic Acid; Hydrogel, Polyethylene Glycol Dimethacrylate; Hydrogels; Hydrogen-Ion Concentration; Imidazoles; Ions; Kinetics; Maleates; Models, Chemical; Serum Albumin; Spectroscopy, Fourier Transform Infrared; Thiocyanates; Time Factors; Water

The task of assigning resonances in proton nuclear magnetic resonance spectra of paramagnetic heme proteins can be an arduous process, but with the development of multi-dimensional NMR methods the situation has improved. It is demonstrated here that two-dimensional exchange spectroscopic experiments can be used to obtain to assignment correlations for the heme protons of methydroxy-, metthiocyano-, metaquo-, and metimidazole-myoglobin forms. All the assignments are unambiguous and straightforward when the temperature and mixing times are adjusted to minimize nuclear Overhauser cross-peaks from each complex. Moreover, saturation transfer experiments allow the study of ligand binding kinetics. The exchange rates between metaquo- and metimidazole- (or methyl substituted imidazole) myoglobin complexes are estimated. The differences between the exchange rates reflect differences in the hydrophobic and steric interactions between the ligands and the protein moiety.

Topics: Animals; Horses; Imidazoles; Myoglobin; Nuclear Magnetic Resonance, Biomolecular; Thiocyanates; Water