Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 13, 2006
Publication Date: May 31, 2006
Citation: Momany, F.A., Willett, J.L. 2006. Molecular dynamics simulations of a cyclic-DP-240 amylose fragment: glass transition temperature study [abstract]. 37th Great Lakes Regional Meeting. p.173. Technical Abstract: Molecular dynamics simulations using AMB06C, an in-house carbohydrate force field, (NPT ensembles, 1 atm.) were carried out on a periodic cell that contained a cyclic-DP-240 amylose fragment and TIP3P water molecules. Molecular motions of the amylose fragment and water molecules at different levels of hydration are examined at temperatures above and below the glass transition temperatures. The amorphous cell was constructured as described previously, through successive dynamic equilibration steps at temperatures above the assumed Tg value and the temperature successively lowered until several temperature points were obtained below Tg. Each dynamics simulation was continued until the volume drift stopped and remained constant for several hundred picoseconds. The final Tg values were found by noting the discontinuity in slope of the volume (V), potential energy (PE), or density, v.s. 1/T. The changes in flexibility and motion of the amylose chains as well as differences in diffusion coefficients of water molecules are described.