Iron and copper binding by fungal phenolic polymers: an electron spin resonance study

Abstract

In an electron spin resonance (ESR) survey of fungal phenolic polymers and melanins, it was found that the phenolic polymers fromEpicoccum purpurascens andPenicillium funiculosum displayed hyperfine splitting, indicating the presence of transition metal bonding. The ESR parameters agree well with those of iron and copper organic complexes. Further, the copper-complex ESR parameters were similar to those reported for mixed complexes of copper, bipyridyl and dicarboxylic acids; this suggests that nitrogen-containing groups from the proteinaceous moiety are involved in the process. Acid hydrolysis removed the proteins and metals, but the hydrolyzed polymers were still able to remove 72% of the copper present in a 0.5× 10–4 M solution. It was concluded that fungal phenolic polymers, which constitute a part of the soil humus, may play an important role in the translocation of metal ions and their availability to biological systems.