14 research outputs found
Hydrophobic and ionic-interactions in bulk and confined water with implications for collapse and folding of proteins
Water and water-mediated interactions determine thermodynamic and kinetics of
protein folding, protein aggregation and self-assembly in confined spaces. To
obtain insights into the role of water in the context of folding problems, we
describe computer simulations of a few related model systems. The dynamics of
collapse of eicosane shows that upon expulsion of water the linear hydrocarbon
chain adopts an ordered helical hairpin structure with 1.5 turns. The structure
of dimer of eicosane molecules has two well ordered helical hairpins that are
stacked perpendicular to each other. As a prelude to studying folding in
confined spaces we used simulations to understand changes in hydrophobic and
ionic interactions in nano droplets. Solvation of hydrophobic and charged
species change drastically in nano water droplets. Hydrophobic species are
localized at the boundary. The tendency of ions to be at the boundary where
water density is low increases as the charge density decreases. Interaction
between hydrophobic, polar, and charged residue are also profoundly altered in
confined spaces. Using the results of computer simulations and accounting for
loss of chain entropy upon confinement we argue and then demonstrate, using
simulations in explicit water, that ordered states of generic amphiphilic
peptide sequences should be stabilized in cylindrical nanopores
Long-Lived Localized Field Configurations in Small Lattices: Application to Oscillons
Long-lived localized field configurations such as breathers, oscillons, or
more complex objects naturally arise in the context of a wide range of
nonlinear models in different numbers of spatial dimensions. We present a
numerical method, which we call the {\it adiabatic damping method}, designed to
study such configurations in small lattices. Using 3-dimensional oscillons in
models as an example, we show that the method accurately (to a part in
10^5 or better) reproduces results obtained with static or dynamically
expanding lattices, dramatically cutting down in integration time. We further
present new results for 2-dimensional oscillons, whose lifetimes would be
prohibitively long to study with conventional methods.Comment: LaTeX, 8 pages using RevTeX. 6 PostScript figures include