Revival of collective water structure and dynamics in reverse micelles brought about by protein encapsulation

Abstract

In this computational study, we investigate the behaviour of a protein in water encapsulated in a zwitterionic/neutral reverse micelle as a cellular mimetic. Addressing the discussion if current force fields are apt to correctly describe crowded/encapsulated environments, we apply an upscaling of the non-bonded, non-electrostatic interactions of protein and/or surfactants with the water component. Based on the thorough analysis of single-particle rotational motion of water and ubiquitin molecules we find retardation near the interfaces and a bulk-like core. This single-particle analysis is contrasted with the study of collective micellar structure and dynamics. We report a novel mechanism of depolarization inside the RM under the general LeChatelier principle of reverse micelle adaptation to the surrounding low-dielectric immersion medium. The relation of this mechanism to other mechanisms of minimum polarization in RMs is discussed.