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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.