Self Assembly Of AOT Reverse Micelles With/without Peptides

Abstract

We are interested in understanding the dynamics and stability of proteins under confinement. To study the reverse micelle formation process and the peptide dynamics inside reverse micelle we performed molecular dynamics simulations for two AOT reverse micelle self-assembly systems, one without peptides and the other with two octa-peptides (AKAAAKA). The self-assembled systems are water-in-oil micro-emulsion systems, and each of them has a 200 ns long simulation time. The other three components of the systems are sodium ions, water and isooctane. The water to surfactant ratio for both of the systems is 6. Reverse micelles form in a quick, spontaneous way. The peptides get encapsulated during the self-assembly and are located at the inner face of the reverse micelle close to the AOT surfactants. The two peptides adopt different conformations, unfolded and alpha-helical, respectively. The peptides are encapsulated in separate reverse micelles. The encapsulated peptides have high coordination with AOT head groups and sodium ions. They experienced low hydration environment and showed much slower dynamics inside the reverse micelle. We find that the dynamics of peptides inside reverse micelle is very different from that in bulk water.This work is funded by the National Science Foundation grant DMR-0117792 and RPI. We gratefully acknowledge a SUR grant from IBM that provided the computer resources to do this work.