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The formation of sodium dodecylsulfate (SDS) micelles in water and heavy water at different pressures and temperatures using molecular dynamics simulations was used to analyze their stability and structure under different conditions and to evaluate the agreement with existing experiments. The results show the assembling of micelles at 1 bar and the presence of larger aggregates under high pressure (over 3 kbar). These large aggregates are not micelles but small finite pieces of bilayers in rod-like shapes. The results obtained using systems at different temperatures showed that both high and low temperatures produce lamellar structures. It is well-known that micelles expose polar residues to water and leave non-polar residues inside where they interact via hydrophobic interactions. High pressure as well as low and high temperatures inhibit the hydrophobic interactions, and under these conditions other structures are produced instead of micelles. This process seems to be similar to protein denaturation under certain temperatures and pressures.

The cold denaturation of globular proteins is a process that can be caused by increasing pressure or decreasing the temperature. Currently, the action mechanism of this process has not been clearly understood, raising an interesting debate on the matter. We have studied the process of cold denaturation using molecular dynamics simulations of the frataxin system Yfh1, which has a dynamic experimental characterization of unfolding at low and high temperatures. The frataxin model here studied allows a comparative analysis using experimental data. Furthermore, we monitored the cold denaturation process of frataxin and also investigated the effect under the high-pressure regime. For a better understanding of the dynamics and structural properties of the cold denaturation, we also analyzed the MD trajectories using essentials dynamic. The results indicate that changes in the structure of water by the effect of pressure and low temperatures destabilize the hydrophobic interaction modifying the solvation and the system volume leading to protein denaturation. Proteins 2016; 85:125-136. © 2016 Wiley Periodicals, Inc.