Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Biophys J. 2004 Jul;87(1):640-7.

New aspects of the alpha-helix to beta-sheet transition in stretched hard alpha-keratin fibers.

Author information

  • 1Laboratoire pour l'Utilisation du Rayonnement, Centre Universitaire Paris-Sud, 91898, Orsay cedex, France.

Abstract

The putative transformation of alpha-helices into beta-sheets has been studied for more than 50 years in the case of hard alpha-keratin. In a previous study of stretched keratin fibers, we specified the conditions for beta-sheet appearance within horsehair: the formation of beta-sheets requires at least 30% relative humidity. However, this phenomenon was observed in the whole tissue. Then there was no clear chemical identification of the beta-sheets (keratin or matrix proteins) and the exact location of the beta-sheets across the fiber could not be specified. In this study, using wide-angle x-ray scattering and high spatial resolution infrared microspectroscopy, we could determine and characterize the structural elements across hair sections stretched in water, which provides new information about the aforementioned transition. Our results show that the process can be split into three steps: 1), unraveling of the alpha-helical coiled-coil domains, which starts at roughly 5% macroscopic strain; 2), further transformation of the unraveled coiled-coils into beta-sheet structures, which occurs above roughly 20% macroscopic strain; and 3), spatial expanding of the beta-structured zones from the sample center to its periphery.

PMID:
15240497
[PubMed - indexed for MEDLINE]
PMCID:
PMC1304386
Free PMC Article

Images from this publication.See all images (5)Free text

FIGURE 1
FIGURE 2
FIGURE 3
FIGURE 4
FIGURE 5
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science Icon for PubMed Central
    Loading ...
    Write to the Help Desk