Structural transitions in the polyalanine alpha-helix under uniaxial strain.
We analyzed the response to strain of an infinite polyalanine chain in the alpha-helical conformation using density functional theory. Under compressive strain the alpha-helix is found to undergo structural transitions to a pi-helix when the length of the helix is reduced by more than 10%. Under tensile strain the structure changes into a 3(10)-helix when the length is stretched by more than 10%. Our analysis of these transitions shows that they proceed essentially in two steps: At first there is mainly a length change, and only with some delay the helix twist adjusts.
Ireta
Joel
J
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin-Dahlem, Germany. ireta@fhi-berlin.mpg.de
Neugebauer
Jörg
J
Scheffler
Matthias
M
Rojo
Arturo
A
Galván
Marcelo
M