Biophysical Society Thematic Meeting - October 13-15, 2015

Biophysics of Proteins at Surfaces: Assembly, Activation, Signaling

Poster Abstracts

31-POS Board 31 Conformation and Aggregation of Peptides in Bulk vs. Interface Cahit Dalgicdir 2 , Beytullah Ozgur 2 , Mehmet Sayar 1,2 . 1 Koc University, Chemical and Biological Engineering Department, Istanbul, Turkey, 2 Koc University, Computational Science and Engineering Program, Istanbul, Turkey. Conformation and assembly of proteins and peptides are not solely determined by their sequence, but are also strongly dependent on their environment. Interfaces, whether they are macroscopic (e.g. air/water interface, membrane), or molecular (e.g. surrounding molecules hydrophobic surfaces) strongly influence the conformation of biopolymers by forcing them to partition their hydrophobic and hydrophilic residues. In this study we investigate the conformation of two different peptides in bulk and at the air/water interface. The first molecule is a 14 residue LK model peptide with a sequence composed of leucine and lysine residues. The second molecule is the N-terminal 17 amino acid sequence in huntingtin (htt NT ) which plays an important role in Huntington's disease. By using molecular dynamics and enhanced simulation techniques, we analyzed the conformational behavior of these peptides in bulk water, at the air/water interface, and finally in the presence of other peptides in bulk water and at the air/water interface. We demonstrate the role of the interface in altering both the preferred conformation and the self- assembly behavior of these peptides. By analyzing the potential of mean force curves between two peptides in different environments, we demonstrate that both the conformation and self- assembly behavior for such peptides strongly depends on the interplay between electrostatic forces, hydrophobic effect, and their strong tendency to form backbone hydrogen bonds.

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