EVIDENCE FOR A GLYCIDIC-LIPIDIC MATRIX IN HUMAN NEUROMELANIN, POTENTIALLY RESPONSIBLE FOR THE ENHANCED IRON SEQUESTERING ABILITY OF SUBSTANTIA-NIGRA

The high-resolution solid-state C-13-NMR spectrum of a neuromelanin sp ecimen (from patients dying from nonneurological diseases) is compared with that obtained from enzymatically prepared dopamine-melanin, The main differences between the two spectra suggest the occurrence in neu romelanin of a glycidic/lipidic matrix tightly associated with the mel anin macromolecule. Atomic emission spectroscopy revealed high iron co ntent (1.5%) in the neuromelanin specimen, in full agreement with prev ious reports. These observations support the view that neuromelanin ac ts as a strong chelating (and insolubilizing) system for iron ions and further suggest that the attack to this compact composite substrate m ay be an important step to allow the release of iron ions responsible for the increased lipid peroxidation reported in the pathogenesis of P arkinson's disease.