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Different membrane order measurement techniques are not mutually consistent

delete2023-03-01
delete19
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OA
AI
A
Ankur Gupta
M
Mamata Kallianpur
D
Debsankar Saha Roy
O
Oskar Engberg
H
Hirak Chakrabarty
D
Daniel Huster *
S
Sudipta Maiti *
DOI:10.1016/j.bpj.2022.08.029delete
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Abstract

Abstract

En 中文
Membrane orderis a term commonly used to describe the elastic and mechanical properties of the lipid bilayer, though its exact meaning is somewhat context-and method dependent. These mechanical properties of the membrane control many cellular functions and are measured using various biophysical techniques. Here, we ask if the results obtained from various techniques are mutually consistent. Such consistency cannot be assumed a priori because these techniques probe different spatial locations and different spatial and temporal scales. We evaluate the change of membrane order induced by se-rotonin using nine different techniques in lipid bilayers of three different compositions. Serotonin is an important neurotransmitter present at 100s of mM concentrations in neurotransmitter vesicles, and therefore its interaction with the lipid bilayer is biolog-ically relevant. Our measurement tools include fluorescence of lipophilic dyes (Nile Red, Laurdan, TMA-DPH, DPH), whose properties are a function of membrane order; atomic force spectroscopy, which provides a measure of the force required to indent the lipid bilayer; 2H solid-state NMR spectroscopy, which measures the molecular order of the lipid acyl chain segments; fluorescence correlation spectroscopy, which provides a measure of the diffusivity of the probe in the membrane; and Raman spectroscopy, where spectral intensity ratios are affected by acyl chain order. We find that different measures often do not corre-late with each other and sometimes even yield conflicting results. We conclude that no probe provides a general measure of membrane order and that any inference based on the change of membrane order measured by a particular probe may be unreliable.
Keywords:
GENERALIZED POLARIZATION
PHOSPHOLIPID-VESICLES
LIPID PHASES
CHOLESTEROL
SPECTROSCOPY
SEROTONIN
MODEL
NMR
ORGANIZATION
GRAMICIDIN
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Journal

Biophysical Journal cover
Biophysical Journal
IF:
3.1
Papers:
5.0W
Citations:
4.4W

Organization

L
Leipzig University
Scholars:
2.0W
Papers: 1.6W
Citations: 17
S
Sambalpur University
Scholars:
560
Papers: 443
Citations: 0