The Mo(VI)- and Cu(II)-binding properties of uronic acids at physiolog
ical pH have been examined by polarography. The metals have been confi
rmed to retain their original oxidation states on binding to the uroni
c acids and the molybdenum is most likely to be present in the form of
an oxo-cation (Mo2O52+). These results support those obtained earlier
by H-1 and C-13 NMR studies.