Journal
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS
Volume 1784, Issue 11, Pages 1570-1577Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbapap.2008.08.007
Keywords
Amyloid disease; Fibril dissociation; Free radicals; Polyphenols; Electron spin resonance; Self-Assembly
Categories
Funding
- Israel Science Foundation
- Deutsch-Israelische Projektkooperation
- Lady Davis Chair of Biochemistry
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Fibrillization of amyloid polypeptides is accompanied by formation of reactive oxygen species (ROS), which, in turn, is assumed to further promote amyloid-related pathologies. Different polyphenols, all of which are established antioxidants, cause dissociation of amyloid fibrils. This study addresses the latter, poorly understood process. Specifically, we have investigated the dissociation of A beta(42) fibrils by six different polyphenols, using electron microscopy and spectrofluorometric analysis. Simultanously, we have monitored the production of ROS using electron spin resonance (ESR) and the commercially available peroxide assay kit. Using the same methods we found that curcumin, one of the most potent destabilizing agents of A beta(42), induced dissociation of fibrils of other amyloid polypeptides [A beta(40), A beta(42)Nle35, islet amyloid polypeptide and a fragment of alpha-synuclein]. When the solution contained traces of transition metal, all the dissociation reactions were accompanied by ROS formation, independent of the presence of a methionine residue. Kinetic studies show that the formation of ROS lags behind dissociation, indicating that if casual relationship exists between these two processes, then ROS formation may be considered a consequence and not a cause of dissociation. These findings open new avenues in amyloid research that will be required to gain further understanding of our results and of their implications. (C) 2008 Elsevier B.V. All rights reserved.
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