Volume-energy correlations in the slow degrees of freedom of computer-simulated phospholipid membranes

TL;DR

This study uses molecular dynamics simulations to reveal strong volume-energy correlations in phospholipid membranes, showing these correlations increase near phase transitions and are consistent across different membrane types.

Contribution

It provides the first direct computational evidence of strong volume-energy correlations in fluid-phase phospholipid membranes, extending previous experimental findings.

Findings

Correlation coefficients range from 0.81 to 0.89 across membranes.

Correlations increase as the phase transition is approached.

Consistent correlations observed in three different membrane types.

Abstract

Constant-pressure molecular-dynamics simulations of phospholipid membranes in the fluid phase reveal strong correlations between equilibrium fluctuations of volume and energy on the nanosecond time-scale. The existence of strong volume-energy correlations was previously deduced indirectly by Heimburg from experiments focusing on the phase transition between the fluid and the ordered gel phases. The correlations, which are reported here for three different membranes (DMPC, DMPS-Na, and DMPSH), have volume-energy correlation coefficients ranging from 0.81 to 0.89. The DMPC membrane was studied at two temperatures showing that the correlation coefficient increases as the phase transition is approached.