Regensburg 2000 – scientific programme
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SYBP: Biologie und Physik
SYBP 3: POSTER
SYBP 3.8: Poster
Thursday, March 30, 2000, 15:00–18:00, D
Ab-initio study of polyalanine secondary structure deformation induced by uniaxial pressure — •Joel Ireta1, Arturo Rojo2, Marcelo Galván2, Jörg Neugebauer1, and Matthias Scheffler1 — 1Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin — 2Universidad Autónoma Metropolitana-Iztapalapa, A.P. 55-534, México D.F. 09340
Studying polypeptides under pressure is very informative in order to reach a better understanding of the structure and molecular basis of the stability of proteins. However, knowledge of the fundamental mechanisms, that control the response of polypeptides to mechanical deformations, is still shallow. This work focus on the analysis of one of the possible mechanical deformations that must occur during the compression of a protein: the compression of an alpha-helix along the helix axis.
Polyalanine was used in this work to model a typical right-handed alpha-helix. The study was carried out employing density-functional theory and ab initio pseudopotentials[1,2], together with the generalized gradient approximation[3] of the exchange-correlation energy functional. Uniaxial pressure was modeled by reducing the unit cell size along helix axis and relaxing the structure at each point.
From our results we find the helix under compression to present two different responses. For the elastic regime (small pitch changes) only structural changes are observed, but for the plastic regime (large pitch changes) electronic as well structural changes are induced.
We will describe the role of hydrogen-bonds, peptide-bond rigidity and the electronic structure in the transition from the elastic to plastic regime.