EPR study on vanadyl and vanadate ion retention by a thermotolerant yeast

The retention of vanadyl(IV) and vanadate(V) ions by Hansenula polymorpha, a thermotolerant yeast, has been studied by EPR spectroscopy. Vanadyl ions were retained as mobile complexes associated with relatively low molecular weight ligands as well as immobilized complexes formed with high molecular weight residues, the donor atoms of which are probably oxygens or deprotonated hydroxyls. The distribution of vanadyl ions between mobile and immobilized complex species is a function of the metal concentration as well as of the contact time. Vanadate ions were reduced by cellular components to vanadyl ions. © 1991.