Abstract: Neurotoxic, redox-competent Alzheimer’s b-amyloid is released from lipid membrane by methionine oxidation

J Biol Chem. 2003 Aug 18 [Epub ahead of print].

Barnham KJ, Ciccotosto GD, Tickler AK, Ali FE, Smith DG, Williamson NA, Lam YH, Carrington D, Tew D, Kocak G, Volitakis I, Separovic F, Barrow CJ, Wade JD, Masters CL, Cherny RA, Curtain CC, Bush AI, Cappai R.

Department of Pathology, University of Melbourne, Melbourne, Victoria 3010.

The amyloid beta-peptide is toxic to neurons and it is believed that this toxicity plays a central role in the progression of Alzheimers disease. The mechanism of this toxicity is contentious. Here we report that an Abeta peptide with the sulfur atom of Met35 oxidized to a sulfoxide (Met(O)Abeta) is toxic to neuronal cells and this toxicity is attenuated by the metal chelator clioquinol and completely rescued by catalase implicating the same toxicity mechanism. However, unlike the unoxidized peptide, Met(O)Abeta is unable to penetrate lipid membranes to form ion channel-like structures and beta-sheet formation is inhibited, phenomena that are central to some theories for Ab toxicity. Our results show that, like the unoxidized peptide, Met(O)Abeta will coordinate Cu2+ and reduce the oxidation state of the metal, and still produce H2O2. We hypothesize that Met(O)Abeta production contributes to the elevation of soluble Abeta seen in the brain in AD.

PMID: 12925530 [PubMed – as supplied by publisher]

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