Molecular oxygen as a probe molecule in EPR spin labeling studies of membrane structure and dynamics

doi:10.3390/oxygen2030021

Molecular oxygen as a probe molecule in EPR spin labeling studies of membrane structure and dynamics

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Molecular oxygen as a probe molecule in EPR spin labeling studies of membrane structure and dynamics

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Bibliographic description

title:	Molecular oxygen as a probe molecule in EPR spin labeling studies of membrane structure and dynamics
author:	Subczynski Witold K., Widomska Justyna, Raguz Marija, Pasenkiewicz-Gierula Marta
journal title:	Oxygen
volume:	2
issue:	3
date of publication :	2022
pages:	295-316
ISSN:	2673-9801
eISSN:	2673-9801
DOI:	10.3390/oxygen2030021
notes:	Bibliogr. s. 312-316
language:	English
journal language:	English
abstract in English:	Molecular oxygen ($O_{2}$) is the perfect probe molecule for membrane studies carried out using the saturation recovery EPR technique. O2 is a small, paramagnetic, hydrophobic enough molecule that easily partitions into a membrane’s different phases and domains. In membrane studies, the saturation recovery EPR method requires two paramagnetic probes: a lipid-analog nitroxide spin label and an oxygen molecule. The experimentally derived parameters of this method are the spin–lattice relaxation times ($T_{1}s$) of spin labels and rates of bimolecular collisions between $O_{2}$ and the nitroxide fragment. Thanks to the long T1 of lipid spin labels (from 1 to 10 µs), the approach is very sensitive to changes of the local (around the nitroxide fragment) $O_{2}$ diffusion-concentration product. Small variations in the lipid packing affect $O_{2}$ solubility and $O_{2}$ diffusion, which can be detected by the shortening of $T_{1}$ of spin labels. Using $O_{2}$ as a probe molecule and a different lipid spin label inserted into specific phases of the membrane and membrane domains allows data about the lateral arrangement of lipid membranes to be obtained. Moreover, using a lipid spin label with the nitroxide fragment attached to its head group or a hydrocarbon chain at different positions also enables data about molecular dynamics and structure at different membrane depths to be obtained. Thus, the method can be used to investigate not only the lateral organization of the membrane (i.e., the presence of membrane domains and phases), but also the depth-dependent membrane structure and dynamics and, hence, the membrane properties in three dimensions.
keywords in English:	molecular oxygen, lipid spin labels, EPR, lipid bilayer membranes, membrane fluidity, membrane domains, cholesterol
affiliation:	Wydział Biochemii, Biofizyki i Biotechnologii : Zakład Biofizyki Obliczeniowej i Bioinformatyki
type:	journal article
subtype:	review article