On measuring the bending modulus of lipid bilayers with cholesterol

TL;DR

This paper examines how different experimental methods affect measurements of the bending modulus of lipid bilayers with cholesterol, clarifying discrepancies and proposing interpretations consistent with equilibrium data.

Contribution

It analyzes conflicting results from transport-based and equilibrium experiments, providing a unified interpretation of the bending modulus measurements.

Findings

Neutron spin echo results can be aligned with equilibrium experiments.

Current NMR relaxation interpretations are ambiguous and alternative explanations are proposed.

The study clarifies how experimental methods influence bending modulus measurements.

Abstract

Regarding the effect on the bending modulus of adding cholesterol to lipid bilayers, recent results using neutron spin echo and nuclear magnetic resonance relaxation methods that involve linear transport properties have conflicted with earlier results from purely equilibrium experiments that do not involve linear transport properties. A general discussion indicates how one can be misled by data obtained by methods that involve linear transport properties. It is then shown specifically how the recent neutron spin echo results can be interpreted to agree with the earlier purely equilibrium experimental results, thereby resolving that conflict. Regarding the nuclear magnetic resonance relaxation method, it is noted that current interpretation of the data is unclear regarding the identity of the modulus that is involved, and an alternative interpretation is explored that does not disagree with the results of the equilibrium experiments.