Session 3A Lectures by Fellows/Associates

Structural and dynamical properties of water near surfactant like peptide nanotubes

Surfactant like peptides (SLPs) nanotubes can be thought of as a class of biocompatible and biodegradable materials which can be used for biomedical applications. The structural and dynamical properties of the water molecules around these self-assembled surfactant-like peptides (SLPs) will be very much different from the bulk water. In view of this, we carried out atomistic molecular dynamics simulations of water molecules near nanotube-like structures where glycine and lysine are taken as the constituents (G6K) for the composition of SLPs. The nanotubes considered were of different dimensions; such as 18x15 (number of peptides on the circumference x number of peptides layers), 18x12 and 16x12 for both charged and neutral analogues. The charged composition consists of protonated nitrogen in lysine subunit and chlorine/bromine as counter ions. It is found that neutral SLPs have less hydrated inner pore consisting of more tetrahedral water compared to their charged analogues. The hydrogen bond lifetime of water-water and water-peptide molecules increases in the inner pore and found to be maximum for charged 16x12 system. Outside the pore, charged analogue of 18x15 have more water-water hydrogen bond lifetime compared to all other systems. However, the protein-water hydrogen bond lifetime was found to be more for neutral analogues outside the pore due to more probable interactions of the SLPs with the water molecules.