ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P171. NMR and PAC Properties of Heavy Metal Ions in Proteins: A
Theoretical Study
K. Rud-Petersen a , K.V. Mikkelsen b , S.P.A. Sauer b , L. Hemmingsen a
a
Natural Sciences,University of Copenhagen,Bülowsvej 17, 1870, Frederiksberg C,Denmark
e-mail: kristian@rud-petersen.dk
b
Chemistry,University of Copenhagen, Denmark
In order to interpret the NMR and perturbed angular correlation (PAC) spectra, we apply ab initio and DFT
calculations to acquire the parameters from model complexes containing the heavy metal ions Cd(II), Hg(II) and
Pb(II). NMR parameters being 2. order properties are known to be very sensitive to conformational changes and
since the atoms are heavy, it is essential to include relativistic effects. The systems to be investigated are both
naturally occurring proteins, de novo designed helix bundles (collaboration with professor V.L. Pecoraro,
University of Michigan), and coordination compounds. PAC and NMR spectroscopy provide complementary
information about both structure and dynamics at the metal ion binding sites, but interpretation of NMR (207Pb,
199Hg and 113Cd) and PAC (204mPb, 199mHg, and 111mCd) spectroscopic data in most cases depend on
empirical methods. Thus, we carry out calculations of electric field gradients (which via the nuclear quadrupole
interaction is the property measured in PAC spectroscopy), chemical shifts and spin-spin coupling constants for
Pb(II), Hg(II) and Cd(II) a series of model systems.
The groups involved have previously, with success, applied both ab initio and DFT methods for calculations of
electric field gradients and chemical shifts in Cd(II) containing compounds [1,2], and recently NMR properties
of mercury containing systems have been investigated in detail [3], providing an excellent basis for the current
investigation.
References:
1. Hemmingsen L., Ryde U. Ab initio calculations of electric field gradients in cadmium complexes J. Phys.
Chem. 1996, 100, 4803-4809.
2. Hemmingsen L., Olsen L., Antony J., Sauer S.P.A. First principle calculations of Cd-113 chemical shifts in
proteins and model systems J. Biol. Inorg. Chem. 2004, 9, 591-599.
3. Autschbach J., Sterzel M. Molecular Dynamics Computational Study of the 199Hg-199Hg NMR Spin-Spin
Coupling Constants of [Hg-Hg-Hg]2+ in SO2 Solution J.Am.Chem.Soc. 2007, 129, 11093-11099.
4. Figure: HgHAH1 metal binding site, made by Monika Stachura
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