COORDINATION ABILITY OF DIGALACTOSAMINE, AND DIGALACTURONIC AND TRIGALACTURONIC ACIDS - POTENTIOMETRIC AND SPECTROSCOPIC STUDIES OF CU(II) COMPLEXES

Potentiometric and spectroscopic (EPR, CD, and absorption spectra) data obtained for digalactosamine and di- and trigalacturonic acid with Cu(II) have shown that the di-sugar binding is usually less efficient than that of monomeric units while the tri-sugar can probably simultaneously use two terminal subunits to coordinate a metal ion. The latter result may have some relevance for metal binding by polysaccharides. All sugar ligands use amino or carboxylate functions as an anchor site, as in monomeric units. Bulky oligomeric ligands protect formation of the bis complexes. This causes the hydrolysis to be a dominant process at higher pH.