title: X-ray absorption near-edge structure micro-spectroscopy study of vanadium speciation in Phycomyces blakesleeanus mycelium.
abstract: Vanadium speciation in the fungus Phycomyces blakesleeanus was examined by X-ray absorption near-edge structure (XANES) spectroscopy, enabling assessment of oxidation states and related molecular symmetries of this transition element in the fungus. The exposure of P. blakesleeanus to two physiologically important vanadium species (V(5+) and V(4+)) resulted in the accumulation of this metal in central compartments of 24 h old mycelia, most probably in vacuoles. Tetrahedral V(5+), octahedral V(4+), and proposed intracellular complexes of V(5+) were detected simultaneously after addition of a physiologically relevant concentration of V(5+) to the mycelium. A substantial fraction of the externally added V(4+) remained mostly in its original form. However, observable variations in the pre-edge-peak intensities in the XANES spectra indicated intracellular complexation and corresponding changes in the molecular coordination symmetry. Vanadate complexation was confirmed by (51)V NMR and Raman spectroscopy, and potential binding compounds including cell-wall constituents (chitosan and/or chitin), (poly)phosphates, DNA, and proteins are proposed. The evidenced vanadate complexation and reduction could also explain the resistance of P. blakesleeanus to high extracellular concentrations of vanadium.
authors.affiliation: Institute for Multidisciplinary Research, Department of Life Sciences, University of Belgrade, Kneza Višeslava 1, 11030, Belgrade, Serbia. mzizic@imsi.rs.
authors.forename: Milan
authors.initials: M
authors.lastname: Žižić
authors.affiliation: CELLS - ALBA, Carretera BP 1413, de Cerdanyola del Vallès a Sant Cugat del Vallès, km. 3,3, 08290, Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Tanja
authors.initials: T
authors.lastname: Dučić
authors.affiliation: Swiss Light Source, Paul Scherrer Institute, 5232, Villigen-PSI, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Grolimund
authors.affiliation: Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000, Belgrade, Serbia.
authors.forename: Danica
authors.initials: D
authors.lastname: Bajuk-Bogdanović
authors.affiliation: Institute for Multidisciplinary Research, Department of Life Sciences, University of Belgrade, Kneza Višeslava 1, 11030, Belgrade, Serbia.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Nikolic
authors.affiliation: Institute for Multidisciplinary Research, Department of Life Sciences, University of Belgrade, Kneza Višeslava 1, 11030, Belgrade, Serbia.
authors.forename: Marina
authors.initials: M
authors.lastname: Stanić
authors.affiliation: Institute for Multidisciplinary Research, Department of Life Sciences, University of Belgrade, Kneza Višeslava 1, 11030, Belgrade, Serbia.
authors.forename: Strahinja
authors.initials: S
authors.lastname: Križak
authors.affiliation: Institute of General and Physical Chemistry, NMR Laboratory, Studentski trg 12-16, 11000, Belgrade, Serbia.
authors.forename: Joanna
authors.initials: J
authors.lastname: Zakrzewska
mesh_terms: D010800:Phycomyces / Q000502:physiology*; D013059:Spectrum Analysis, Raman; D014639:Vanadium / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy / Q000379:methods*
chemical_list: D014639:Vanadium
keywords: Phycomyces blakesleeanus; Raman spectroscopy; Vanadium; X-ray absorption near-edge structure