Exploring the mobility of actinyl ions in the biogeosphere: a spectroscopic and theoretical study of U(VI) complexes with organic phosphate groups


Exploring the mobility of actinyl ions in the biogeosphere: a spectroscopic and theoretical study of U(VI) complexes with organic phosphate groups

Foerstendorf, H.; Tsushima, S.; Brüning, S.; Li, B.

The high affinity of uranyl(VI) ions to distinct functional groups of biomolecules is considered to contribute decisively to the migration behaviour of these metal ions in the biogeosphere [1]. In particular, organic phosphate groups are predestined to form actinide complexes at a physiologically relevant pH level [2]. Because the phosphorylated sites of biomolecules often represent a key role in their proper physiological function, the study on the complexation is of great significance.
In this work, U(VI) complexes of phosphorylated amino acids, namely p-serine and p-tyrosine, were investigated by vibrational spectroscopy serving as model compounds for more complex systems. The spectra obtained demonstrate the high affinity of the actinyl ion to phosphate groups. Contributions from the carboxyl and amino groups to the U(VI) complexes can be neglected.
These results are compared with spectra obtained from our recent investigation with a naturally occurring highly phosphorylated protein, phosvitin [3]. The spectral homologies confirm the suggestion that U(VI) is preferentially bound by organic phosphate groups under physiologically relevant conditions.
The derivation of molecular structures from vibrational spectra can be supported by theoretical approaches, such as density functional theory (DFT) calculations. A series of calculations was performed to reproduce the vibrational spectral data focusing on the frequency range of the vibrational modes of the phosphate groups. A comparison with the experimental data provides additional structural information on a molecular level.

[1] Van Horn, J. D. et al. (2006) Coord. Chem. Rev. 250, 765-775. [2] Barkleit, A. et al. (2008) Dalton Trans., 2879-2886. [3] Li, B. et al. (2010) J. Inorg. Biochem. 104, 718-725.

  • Lecture (Conference)
    Goldschmidt 2011, 14.-19.08.2011, Prague, Czech Republic
  • Open Access Logo Contribution to proceedings
    Goldschmidt 2011, 14.-19.08.2011, Prague, Czech Republic
    Mineralogical Magazine 75(3), Twickenham: Mineralogical Society of Great Britain and Ireland, 0026-461X, 856-856

Downloads

Permalink: https://www.hzdr.de/publications/Publ-15632
Publ.-Id: 15632