Coarse-Grained Molecular Dynamics Modeling of Defective Erythrocyte Membrane and Sickle Hemoglobin Fibers

TL;DR

This paper introduces a coarse-grained molecular dynamics model that simulates the erythrocyte membrane's fluid and elastic properties, enabling large-scale, long-time simulations of membrane behavior under shear stress.

Contribution

It combines lipid bilayer and cytoskeleton modeling in a single CGMD framework, allowing control over membrane properties and studying their effects under shear conditions.

Findings

Shear stress at low strain rates is mainly due to the spectrin network.

Viscosity of the lipid bilayer influences shear stress at higher strain rates.

Reducing spectrin connectivity decreases the membrane's shear modulus.

Abstract

In this work, we develop a two-component coarse-grained molecular dynamics (CGMD) model for simulating the erythrocyte membrane. This proposed model possesses the key feature of combing the lipid bilayer and the erythrocyte cytoskeleton, thus showing both the fluidic behavior of the lipid bilayer and elastic properties of the erythrocyte cytoskeleton. The proposed model facilitates simulations that span large length-scales (~ micrometer) and time-scales (~ ms). By tuning the interaction potential parameters, diffusivity and bending rigidity of the membrane model can be controlled. In the study of the membrane under shearing, we find that in low shear strain rate, the developed shear stress is mainly due to the spectrin network, while the viscosity of the lipid bilayer contributes to the resulting shear stress at higher strain rates. In addition, the effects of the reduction of the spectrin network connectivity on the shear modulus of the membrane are investigated.