Molecular Simulations of Dodecyl-β-maltoside Micelles in Water: Influence of the Headgroup Conformation and Force Field Parameters

Abstract

This paper deals with the development and validation of new potential parameter sets, based on the CHARMM36 and GLYCAM06 force fields, to simulate micelles of the two anomeric forms (α and β) of N-Dodecyl-ß-maltoside (C 12 G 2 ), a surfactant widely used in the extraction and purification of membrane proteins. In this context, properties such as size, shape, internal structure and hydration of the C 12 G 2 anomer micelles were thoroughly investigated by molecular dynamics simulations and the results compared with experiments. Additional simulations were also performed with the older CHARMM22 force field for carbohydrates (Kuttel, M. et al. J. Comp. Chem. 2002, 23, 1236-1243. We find that our CHARMM and GLYCAM parameter sets yields similar results in case of properties related to the micelle structure, but differ for other properties such as the headgroup conformation or the micelle hydration. In agreement with experiments, our results show that for all model potentials the β-C 12 G 2 micelles have a more pronounced ellipsoidal shape than those containing α anomers. The computed radius of gyration is 20.2 Å and 25.4 Å for the α-and β-anomer micelles, respectively. Finally, we show that depending on the potential the water translational diffusion of the interfacial water is 7 -11.5 times slower than that of bulk water due to the entrapment of the water in the micelle crevices. This retardation is independent of the headgroup in α-or β-anomers.

Energetics of clouding and size effects in non-ionic surfactant mixtures: The influence of alkyl chain length and NaCl addition

“…As Drummond and co-workers [29] found on investigating the interfacial microenvironment of micelles of sugar-based surfactants, the region around the head groups is highly aqueous-like, leading to effective dielectric constants of the micelle interface that are nearly twice as high as those typical of ethoxylated surfactants. The existence of a large hydrogen bond network at the surface of C 12 G 2 micelles between water and the head groups, and within the head groups themselves has been recently reported [30]. Similar results have been observed for alkylmonoglucoside surfactants (i.e.…”

Unusual, pH-Induced, Self-Assembly Of Sophorolipid Biosurfactants

“…This value is obtained by comparison with N-dodecyl-β-maltoside (C12G2), in which, according to experimental and modelled data, maltose (a common disaccharide comparable to sophorose) does not contribute to more than 6 Å to the size of C12G2 in its linear conformation (β-anomer). 53 Under these conditions, one expects a cross-sectional radius for SL micelles of approximately 30 Å. In reality, the experimental data measured by SANS are 30% to 50% lower depending on the micellar shape (sphere, ellipsoid or cylinder) in the low ionization degree regime, as discussed before and shown in Table 1.…”

Ligand Modulation of Sidechain Dynamics in a Wild-Type Human GPCR

“…The all-atom MD simulations were performed with the NAMD 2.7 package (Phillips et al, 2005) using the all-atom CHARMM27 force-field with CMAP corrections for proteins (Brooks et al, 2009), and a CHARMM-compatible force-field parameter set for detergents (Abel et al, 2011). CHARMMsuitable parameters for NECA and ZM241385 compounds were generated with the program MATCH (Yesselman et al, 2012).…”