Molecular dynamics simulations of an antifreeze protein at the lipid / water interface

Abstract

The ability of antifreeze proteins (AFP's) and glycoproteins (AFGP's) to prevent damage to certain organisms under cold stress is well established. These molecules have also been shown to prevent chilling damage in some biological membranes and interaction between membranes and AF(G)P's has been observed during chilling events; however, the exact mechanism of membrane stabilization is still not well understood. Molecular modelling is an ideal technique for probing atomistic information in these systems although modelling studies to date have focused on peptide structure and the site and mode, e.g., insertion, of the peptide-membrane interaction. To provide insight into how AF(G)P's may act to stabilize (or destabilize) membranes during phase transitions, we have conducted molecular dynamics (MD) simulations of a solvated dimyristoylphosphatidylcholine (DMPC) lipid bilayer containing an AFP Type I at the lipid/water interface at several temperatures. We present the analysis of several properties of the phospholipid bilayer that are relevant when considering phase transitions. Possible areas for concentrating future research efforts have been highlighted; namely the acyl chain order and the polar headgroups, both of which have been implicated in experimental studies of the stabilization of model membranes by AF(G)P's.