Neurofilament proteins are highly phosphorylated molecules in the axonal co
mpartment of the adult nervous system. We report the structural analysis of
neurofilament proteins after oxidative damage. SDS-PAGE, immunoblotting, c
ircular dichroism, and Fourier transform infrared spectroscopy were used to
investigate the relative sensitivity of neurofilaments to oxidative stress
and to identify changes in their molecular organization. An ascorbate-Fe+3
-O-2 buffer system as well as catechols were used to generate free radicals
on a substrate of phosphorylated and dephosphorylated neurofilaments. By F
ourier Transform Infrared spectroscopy and circular dichroism, we establish
ed that the neurofilament secondary structure is mainly composed of alpha -
helices and that after free radical damage of the peptide backbone of neuro
filaments, those helices are partly modified into beta -sheet and random co
il structures. These characteristic reorganizations of the neurofilament st
ructure after oxidative exposure suggest that free radical activity might p
lay an important role in the biogenesis of the cytoplasmic inclusions found
in several neurodegenerative diseases.