Amyloid β (Aβ) peptides fibril formation and deposition is considered to be the principal pathological hallmark of Alzheimer?s disease (AD). However, it remains obscure why AD is precluded by rat/mouse despite the high sequence identity (97%) of rat/mouse Aβ to its human homologue. Based on the recently proposed redox chemistry-based pathogenic model of neurodegenerative diseases, we hypothesize that the lack of key residues of rat/mouse Aβ compared with the human counterpart may account for why rat/mouse is free of AD. At the same time, we propose a new possible redox chemistry-based pathogenic model of AD based on the experimental observations of certain residues in triggering Aβ aggregation. Moreover, it is also interesting to note that non-mammalian Xenopus Aβ contains all the redox chemistry-related key residues and whether it implies that Xenopus Aβ possesses high amyloidogenic potency remains to be determined by further experimental study.

Key words: Alzheimer?s disease; Amyloid β peptides; Redox chemistry; and Metal ions.