Cu(II) binding to monomeric, oligomeric, and fibrillar forms of the Alzheimer's disease amyloid-beta peptide.
Biochemistry
; 47(17): 5006-16, 2008 Apr 29.
Article
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| MEDLINE
| ID: mdl-18393444
ABSTRACT
Copper has been proposed to play a role in Alzheimer's disease through interactions with the amyoid-beta (Abeta) peptide. The coordination environment of bound copper as a function of CuAbeta stoichiometry and Abeta oligomerization state are particularly contentious. Using low-temperature electron paramagnetic resonance (EPR) spectroscopy, we spectroscopically distinguish two Cu(II) binding sites on both soluble and fibrillar Abeta (for site 1, A parallel = 168 +/- 1 G and g parallel = 2.268; for site 2, A parallel = 157 +/- 2 G and g parallel = 2.303). When fibrils that have been incubated with more than 1 equiv of Cu(II) are washed, the second Cu(II) ion is removed, indicating that it is only weakly bound to the fibrils. No change in the Cu(II) coordination environment is detected by EPR spectroscopy of Cu(II) with Abeta (11 ratio) collected as a function of Abeta fibrillization time, which indicates that the Cu(II) environment is independent of Abeta oligomeric state. The initial Cu(II)-Abeta complexes go on to form Cu(II)-containing Abeta fibrils. Transmission electron microscopy images of Abeta fibrils before and after Cu(II) addition are the same, showing that once incorporated, Cu(II) does not affect fibrillar structure; however, the presence of Cu(II) appears to induce fibril-fibril association. On the basis of our results, we propose a model for Cu(II) binding to Abeta during fibrillization that is independent of peptide oligomeric state.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Péptidos beta-Amiloides
/
Cobre
Idioma:
En
Revista:
Biochemistry
Año:
2008
Tipo del documento:
Article
País de afiliación:
Estados Unidos