CD studies on films of amyloid proteins and polypeptides: Quantitative g-factor analysis indicates a common folding motif
✍ Scribed by Peter McPhie
- Book ID
- 101718311
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2004
- Tongue
- English
- Weight
- 125 KB
- Volume
- 75
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
Irrespective of the constituent protein, all amyloid fibrils show similar morphology in the electron microscope and x‐ray diffraction patterns characteristic of a “cross‐β” structure, with extended β‐strands perpendicular to the fibril's long axis. Little is known about the amount or type of this structure. I have measured CD spectra of films formed from a number of amyloid proteins and polypeptides, and estimated their contents of extended secondary structure, by analysis of their g‐factor spectra, the ratio of the CD and absorbance signals (P. McPhie, Analytical Biochemistry, 2001, Vol. 293, pp. 109–119). Amyloid films of Aβ‐(1–40) peptide, β‐2‐microglobulin, insulin, and three homopolypeptides show very intense CD spectra, compatible with the presence of a β‐helix‐like structure, arranged in a common framework in the fibrils. The extent of this structure was estimated as 45–80% in the protein fibrils and 30–80% in the polypeptide fibrils. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004