Biomembrane solubilization mechanism by Triton X-100: a computational study of the three stage model

Abstract

The solubilization mechanism of lipid membranes in the presence of Triton X-100 (TX-100) is investigated at molecular resolution using molecular dynamics (MD) simulations. Thanks to the large time and length scales accessible by the hybrid particle-field formulation of the models employed here, the complex process of membrane solubilization has been studied, with the goal of verifying the three stage model reported in the literature. DPPC lipid bilayers and vesicles have been studied at different concentrations of the TX-100 detergent employing coarse grained (CG) models. Systems up to ∼600.000 beads, corresponding to more than 2 millions heavy atoms, have been simulated. Moreover, in order to clarify several experimental pieces of evidence, both slow and fast detergent partition scenarios have been investigated. Flat and curved (vesicles) lipid bilayer surfaces, interacting with TX-100, have been considered to study the curvature effects on the detergent partition rate in the membrane. Shape and conformational changes of mixed DPPC/TX-100 vesicles, as a function of TX-100 content, have also been studied. In particular, high curvature surfaces, corresponding to a higher local TX-100 content, promote a membrane rupture. In flat lipid surfaces, on the time scale simulated the detergent partition is almost absent, following a different pathway of the solubilization membrane mechanism.

Hybrid Particle-Field Model for Conformational Dynamics of Peptide Chains

“…20 First application studies on homopolymers and block copolymers 19,21 demonstrated the effectiveness of hPF-MD in describing soft-matter and polymeric materials both at the mesoscale and atomistic resolution. 22 More recently, hPF-MD was used to describe the morphology and dynamics of amphiphilic systems in the aqueous environment, in particular of phospholipids [23][24][25][26] and surfactants, 27,28 paving the way to the possibility of using hPF-MD to investigate biological systems. 29 Among the biological polymers, the development of computational multi-scaling approaches for proteins is particularly challenging, but of great interest.…”

Are TiO2 nanoparticles safe for photocatalysis in aqueous media?

“…22 Prior to functionalization of the macroporous supports, Triton X-100 was used to disperse the TiO 2 nanoparticles. Despite their demonstrated capability of degrading biomembrane proteins and lipids, 23 causing severe impairment of cells and tissues through release of intracellular components, an irrelevant toxic effect was veried for the nanoparticles released from HTS250 C ( Fig. 2C), which even showed slightly lower toxicity than the heat-treated nanoparticles.…”

Can Polarity-Inverted Surfactants Self-Assemble in Nonpolar Solvents?

“…hPF-MD simulations Figure 1 shows the CG mapping chosen for ADOH, while in Table I we report the bead interaction matrixχ ij used in the present work. Theχ values for C 6 H 12 and ADOH were selected from chemically similar moieties of Triton X-100 from Ref [29]. CG simulations were run in the N V T ensemble using the OCCAM software [38].…”