TY - JOUR

T1 - Lipid chain mobility and packing in DOPC bilayers at cryogenic temperatures

AU - Golysheva, Elena A.

AU - Dzuba, Sergei A.

N1 - Copyright © 2019 Elsevier B.V. All rights reserved.

PY - 2020/1/1

Y1 - 2020/1/1

N2 - Low-temperature molecular mobility and packing in biological tissues are important for their survival upon cryopreservation. Electron paramagnetic resonance (EPR) in its pulsed version of electron spin echo (ESE) allows studying stochastic librations of spin-labeled molecules, the type of motion which dominates at low temperatures. These librations are characterized by the parameter <α2>τc where <α2> is the mean squared angular amplitude and τc is the correlation time for the motion. This parameter is known to be larger for higher temperature and for looser intermolecular structure. In this work, ESE data for the bilayers comprised of doubly-unsaturated DOPC (dioleoyl-glycero-phosphocholine) lipids and mono-unsaturated POPC (palmitoyl-oleoyl-glycero-phosphocholine) lipids with spin-labeled stearic acids added were obtained in the temperature range between 80 and 210 K; the results were compared also with the previously obtained data for fully-saturated DPPC (dipalmitoyl-glycero-phosphocholine) lipid bilayers [J. Phys. Chem. B 2014, 118, 12,478–12,485; Appl. Magn. Reson. 2018, 49, 1369–1383]. It turned out that for DOPC bilayers the <α2>τc values are of intermediate magnitude between those for POPC and DPPC bilayers, which implies an intermediate density of lipid packing. A possible explanation of this result could be rearrangement at cryogenic temperatures of the DOPC lipid tails, with their terminal segments folding cooperatively. This interpretation is also in agreement with the known thermodynamic properties of gel-fluid transition for DOPC bilayer.

AB - Low-temperature molecular mobility and packing in biological tissues are important for their survival upon cryopreservation. Electron paramagnetic resonance (EPR) in its pulsed version of electron spin echo (ESE) allows studying stochastic librations of spin-labeled molecules, the type of motion which dominates at low temperatures. These librations are characterized by the parameter <α2>τc where <α2> is the mean squared angular amplitude and τc is the correlation time for the motion. This parameter is known to be larger for higher temperature and for looser intermolecular structure. In this work, ESE data for the bilayers comprised of doubly-unsaturated DOPC (dioleoyl-glycero-phosphocholine) lipids and mono-unsaturated POPC (palmitoyl-oleoyl-glycero-phosphocholine) lipids with spin-labeled stearic acids added were obtained in the temperature range between 80 and 210 K; the results were compared also with the previously obtained data for fully-saturated DPPC (dipalmitoyl-glycero-phosphocholine) lipid bilayers [J. Phys. Chem. B 2014, 118, 12,478–12,485; Appl. Magn. Reson. 2018, 49, 1369–1383]. It turned out that for DOPC bilayers the <α2>τc values are of intermediate magnitude between those for POPC and DPPC bilayers, which implies an intermediate density of lipid packing. A possible explanation of this result could be rearrangement at cryogenic temperatures of the DOPC lipid tails, with their terminal segments folding cooperatively. This interpretation is also in agreement with the known thermodynamic properties of gel-fluid transition for DOPC bilayer.

KW - Biological membranes

KW - Cryopreservation

KW - Electron spin echo

KW - EPR

KW - Gel-fluid transition

KW - Spin labels

KW - Stearic acid

KW - CHOLESTEROL

KW - ECHO

KW - MEMBRANES

KW - MODEL

KW - DYNAMICAL TRANSITION

KW - GLASS-TRANSITION

KW - ELECTRON-PARAMAGNETIC-RESONANCE

KW - ORDER PARAMETERS

KW - SPIN-LABELED LIPIDS

KW - IONIC LIQUIDS

UR - http://www.scopus.com/inward/record.url?scp=85074437477&partnerID=8YFLogxK

U2 - 10.1016/j.chemphyslip.2019.104817

DO - 10.1016/j.chemphyslip.2019.104817

M3 - Article

C2 - 31525380

AN - SCOPUS:85074437477

VL - 226

JO - Chemistry and Physics of Lipids

JF - Chemistry and Physics of Lipids

SN - 0009-3084

M1 - 104817

ER -