Temperature-Dependent Atomic Models of Detergent Micelles Refined against Small-Angle X-Ray Scattering Data

Abstract

Surfactants have found a wide range of industrial and scientific applications. In particular, detergent micelles are used as lipid membrane mimics to solubilize membrane proteins for functional and structural characterization. However, an atomic-level understanding of surfactants remains limited because many experiments provide only low-resolution structural information on surfactant aggregates. In this work, small-angle X-ray scattering is combined with molecular dynamics simulations to derive fully atomic models of two maltoside micelles at temperatures between 10 °C and 70 °C. The micelles take the shape of general tri-axial ellipsoids and decrease in size and aggregation number with increasing temperature. Density profiles of hydrophobic groups and water along the three principal axes reveal that the minor micelle axis closely mimics lipid membranes. The results suggest that coupling atomic simulations with low-resolution data allows the structural characterization of surfactant aggregates.