Research Information System
INTERNATIONAL JOURNAL OF MODERN PHYSICS C, vol.17, no.2, pp.235-246, 2006 (Journal Indexed in SCI)
In order to provide insights into the misfolding mechanism and the subsequent aggregate formation which cause what are known as the neurodegenerative polyglutamine diseases, we have simulated a 10-residue polyglutamine (poly-Q) chain in vacuum and in solvent by multicanonical method, which enabled us to study the system in a wide temperature range and discuss thermodynamic properties. It is understood that the system in vacuum shows two phase transitions, first of them occur at high temperature that is the well-known helix-coil transition and the second one is a solid-solid transition. However, the poly-Q chain in solvent is in a random coil state at higher temperatures, goes through a conformational change at T = 200 K and assumes predominantly a mixture of anti-parallel beta-sheet and alpha-helix structures at low temperatures. One-residue glutamine dipeptide is also simulated and low-energy stable conformations are identified.