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Alzheimer's Disease Amyloid β Peptide 25-35 Inhibits Lipid Peroxidation as a Result of Its Membrane Interactions

1997; Elsevier BV; Volume: 233; Issue: 3 Linguagem: Inglês

10.1006/bbrc.1997.6547

1090-2104

Mary Walter, Pamela E. Mason, Ronald P. Mason,

Cholinesterase and Neurodegenerative Diseases

The biological activity of the Alzheimer's disease amyloid β protein may be related to modulation of membrane lipid peroxidation. The effect of amyloid β protein fragment 25-35 [Aβ(25-35)] on lipid peroxidation was examined in liposomes enriched with polyunsaturated fatty acids. The activity of Aβ(25-35) was compared to that of Aβ(25-35) with either a scrambled sequence [Aβ(25-35)scram] or a peptide sequence in which methionine was replaced with leucine [Aβ(25-35)−met]. Aβ(25-35) inhibited lipid peroxidation in a dose- and time-dependent manner. The antioxidant activity of Aβ(25-35) was observed at concentrations as low as 10 nM. The relative antioxidant activities of the amyloid β protein fragments were as follows: Aβ(25-35) > Aβ(25-35)−met> Aβ(25-35)scram. The two more potent peptides intercalated into the membrane hydrocarbon core, as determined by small-angle x-ray diffraction approaches. These findings indicate that the amphiphilic Aβ(25-35) peptide inhibits lipid peroxidation at low concentrations as a result of physicochemical interactions with the membrane lipid bilayer.