Catecholamine melanins. Structural changes induced by copper ions.

Melanins synthesized from adrenaline and dopamine in the presence or absence of copper ions were characterized by pyrolysis-gas chromatography-mass spectrometry and by IR and ESR methods. It was shown that Cu2+ are able to induce changes in the melanin structure. Melanins obtained from adrenaline-Cu2+ and dopamine-Cu2+ complexes are composed mainly from monomeric units of the indole type. Melanins synthesized from these catecholamines without Cu2+ contain additionally large amounts of unindolized monomeric units. The structure differences in both types of melanins are reflected in their sorptive abilities and spectroscopic characteristics.