THE INFLUENCE OF O-17 ENRICHED OXYGEN DONOR LIGANDS ON THE ELECTRONIC SPIN RELAXATION BEHAVIOR OF PARAMAGNETIC METAL-IONS Academic Article uri icon

abstract

  • Continuous wave microwave power saturation of high-spin paramagnetic metalloprotein complexes of Co2+ and Fe3+ showed that the value of the saturation parameter P1/2 is influenced by the coordination of oxygen-17 enriched water to the metal ion. No change was observed for H218O or2H2O. Pulse saturation and recovery of paramagnetic high-spin Fe3+ heme proteins identified a fast relaxation component sensitive to isotopic oxygen-17 composition that was assigned to the process of spectral diffusion. It is shown that the change in relaxation time for spectral diffusion can alter the (apparent) spin-lattice relaxation to account for the observed changes in continuous wave microwave power saturation experiments. These changes are shown to correlate with alterations in the extent of covalency between the metal ion and oxygen-donor ligand. The experimental results provide a basis for use of continuous wave microwave saturation to identify the presence of oxygen-donor ligands within the inner coordination shell of high-spin Co2+ or Fe3+ in metalloprotein and small molecule complexes and to qualitatively assess the extent of covalency between the metal ion and the oxygen-donor ligand. 1992 Taylor & Francis Ltd.

published proceedings

  • MOLECULAR PHYSICS

author list (cited authors)

  • WELLS, G. B., YIM, M. B., & MAKINEN, M. W.

citation count

  • 1

complete list of authors

  • WELLS, GB||YIM, MB||MAKINEN, MW

publication date

  • April 1992