After preliminary results obtained for the cap pigment of bay boletus, norbadione A, bandits ability to bind two caesium captions with a positively cooperative mechanism, the postdoctoral research project will start by the study of the exchange process between K+,the natural action bound to norbadione A, with Cs+. A very original combination ofmicrocalorimetry and electro spray mass spectrometry will be used to monitor and quantify this unusual alkali captions exchange. 13C and 133Cs NMR will provide further structural information on the K+ and Cs+ norbadione complexes in solution respectively. The accumulation of divalent heavy metals (Ni(II), Cod(II), Hg(II) and Pb(II)) in mushrooms has been often reported. Therefore the speciation of the corresponding complexes with norbadione A will be thoroughly examined using spectrophotometricand mass spectrometric methods in combination with classical potentiometer. Besidedimeric palinode-type pigments, monomer analogues are also present, sometimes enlarge amounts, in common edible mushrooms. Therefore, four of these catechu- orpyrogallol-type compounds will be studied. The strong binding properties of these moieties suggest the possible participation of Fe(III) or A1(III), transferred from the soils, in order to gather these monomer derivatives and to "mimic" norbadione A withpulvinone-type coordination sites available to chelae monovalent or divalent deleterious metals. The self-assembly mechanism of these polynuclear supramolecular edifices will be studied using a combination of analytical methods and kinetic techniques. This multidisciplinary research project is addressing challenging issues in terms of environmental problems and food quality and safety.
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