Ripple-like instability in the simulated gel phase of finite size phosphocholine bilayers

TY - JOUR

T1 - Ripple-like instability in the simulated gel phase of finite size phosphocholine bilayers

AU - Walter, Vivien

AU - Ruscher, Céline

AU - Gola, Adrien

AU - Marques, Carlos M.

AU - Benzerara, Olivier

AU - Thalmann, Fabrice

N1 - Funding Information: V. W. warmly thanks T.E. de Oliveira for helping with simulations set-up. A.G. acknowledges partial support from the Investissements d’Avenir program “Développement de l’Économie Numérique” through the SMICE project. C.R. acknowledges support from the French National Research Agency , grant ANR-18-CE06-001-01 LatexDry . The authors gratefully acknowledge support from the high performance cluster (HPC) Equip@Meso from the University of Strasbourg, France , through grants no. G2019A131C and G2020A140C . Publisher Copyright: © 2021 Elsevier B.V. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/11/1

Y1 - 2021/11/1

N2 - Atomistic molecular dynamics simulations have reached a degree of maturity that makes it possible to investigate the lipid polymorphism of model bilayers over a wide range of temperatures. However if both the fluid Lα and tilted gel Lβ′ states are routinely obtained, the Pβ′ ripple phase of phosphatidylcholine lipid bilayers is still unsatifactorily described. Performing simulations of lipid bilayers made of different numbers of DPPC (1,2-dipalmitoylphosphatidylcholine) molecules ranging from 32 to 512, we demonstrate that the tilted gel phase Lβ′ expected below the pretransition cannot be obtained for large systems (equal or larger than 94 DPPC molecules) through common simulations settings or temperature treatments. Large systems are instead found in a disordered gel phase which display configurations, topography and energies reminiscent from the ripple phase Pβ′ observed between the pretransition and the main melting transition. We show how the state of the bilayers below the melting transition can be controlled and depends on thermal history and conditions of preparations. A mechanism for the observed topographic instability is suggested.

AB - Atomistic molecular dynamics simulations have reached a degree of maturity that makes it possible to investigate the lipid polymorphism of model bilayers over a wide range of temperatures. However if both the fluid Lα and tilted gel Lβ′ states are routinely obtained, the Pβ′ ripple phase of phosphatidylcholine lipid bilayers is still unsatifactorily described. Performing simulations of lipid bilayers made of different numbers of DPPC (1,2-dipalmitoylphosphatidylcholine) molecules ranging from 32 to 512, we demonstrate that the tilted gel phase Lβ′ expected below the pretransition cannot be obtained for large systems (equal or larger than 94 DPPC molecules) through common simulations settings or temperature treatments. Large systems are instead found in a disordered gel phase which display configurations, topography and energies reminiscent from the ripple phase Pβ′ observed between the pretransition and the main melting transition. We show how the state of the bilayers below the melting transition can be controlled and depends on thermal history and conditions of preparations. A mechanism for the observed topographic instability is suggested.

KW - Lipid bilayers

KW - Molecular dynamics simulations

KW - Phase transition

UR - http://www.scopus.com/inward/record.url?scp=85112004031&partnerID=8YFLogxK

U2 - 10.1016/j.bbamem.2021.183714

DO - 10.1016/j.bbamem.2021.183714

M3 - Article

AN - SCOPUS:85112004031

SN - 0005-2736

VL - 1863

JO - Biochimica et Biophysica Acta - Biomembranes

JF - Biochimica et Biophysica Acta - Biomembranes

IS - 11

M1 - 183714

ER -