Senile plaque composition and posttranslational modification of amyloid-beta peptide and associated proteins.

Amyloid deposits are primarily composed of the amyloid-beta protein, although other proteins (and metal ions) also have been colocalized to these lesions. The pattern of oxidative modifications in amyloid plaques is very different to that associated with neurofibrillary tangles and neuronal cell bodies, likely reflecting the different composition of these structures, accessibility of oxidants, the generation of oxidants in and around these structures and the intrinsic antioxidant defense systems to protect these structures. Future studies directed at understanding Abeta interactions with other amyloid components, the role of oxidative modifications in stabilizing amyloid deposits and the determination of protease cleavage sites on Abeta may provide mechanistic insights regarding both amyloid formation and removal.