Interdigitated lamellar phases in the frozen state: Spin-label CW- and FT-EPR

Aloi, Erika; Bartucci, Rosa

doi:10.1016/j.bpc.2019.106229

Cited by 10 publications

(4 citation statements)

References 43 publications

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“…Only on entering the higher temperature regime, the angular amplitudes increase and are larger at the chain termini than at the beginning of the chain comparable to that in DPPC. Similar results have been obtained in lamellae with interdigitated chains formed by mixtures of DPPC and Lyso-palmitoilphosphatidylcholine or induced in DPPC by ethanol ( Aloi and Bartucci, 2019 ). The behavior of the chain-labeled lipids in DHPC is consistent with the interdigitated phase in which the positional isomers at the chain termini are motionally restricted to an extent comparable to those in proximity of the polar/apolar interface ( Boggs et al, 1989 ; Bartucci et al, 1993 ; Oranges et al, 2018 ).…”

Section: Introductionsupporting

confidence: 85%

Librational Dynamics of Spin-Labeled Membranes at Cryogenic Temperatures From Echo-Detected ED-EPR Spectra

Bartucci

Aloi²

2022

Front. Mol. Biosci.

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Methods of electron spin echo of pulse electron paramagnetic resonance (EPR) spectroscopy are increasingly employed to investigate biophysical properties of nitroxide-labeled biosystems at cryogenic temperatures. Two-pulse echo-detected ED-spectra have proven to be valuable tools to describe the librational dynamics in the low-temperature phases of both lipids and proteins in membranes. The motional parameter, α2τC, given by the product of the mean-square angular amplitude, α2, and the rotational correlation time, τC, of the motion, is readily determined from the nitroxide ED-spectra as well as from the W-relaxation rate curves. An independent evaluation of α2 is obtained from the motionally averaged 14N-hyperfine splitting separation in the continuous wave cw-EPR spectra. Finally, the rotational correlation time τC can be estimated by combining ED- and cw-EPR data. In this mini-review, results on the librational dynamics in model and natural membranes are illustrated.

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Section: Introductionsupporting

confidence: 85%

Librational Dynamics of Spin-Labeled Membranes at Cryogenic Temperatures From Echo-Detected ED-EPR Spectra

Bartucci

Aloi²

2022

Front. Mol. Biosci.

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“…4 then provide an additional insight into the character of the microstructure of DESs, because stochastic librations reflect nanoscopic molecular packing in the molecular system under study. 34–40 The data 34,37–39 for lipid bilayers have shown that the Δ W temperature dependence reflects the rigidity/softness of molecular packing in molecular systems: the softer the packing, the weaker the temperature dependence, and the softer the packing, the lower the starting temperature at which the motion appears.…”

Section: Discussionmentioning

confidence: 99%

“…37–39 On these grounds, these motions may deliver unique information on the rigidity of nanoscale molecular packing in the molecular systems under study. Except for the mentioned above ILs, nanoscale molecular packing was studied with pulsed EPR for model biological membranes (lipid bilayers) 37–42 and for proteins. 34,43–45…”

Section: Introductionmentioning

confidence: 99%

Structural properties of supercooled deep eutectic solvents: choline chloride–thiourea compared to reline

Golysheva

Maslennikova

Baranov

et al. 2022

Phys. Chem. Chem. Phys.

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“…Further, interaction of free fatty acids with proteins [ 24 ] and interaction of sugars with biological membranes [ 25 ] was investigated. Stochastic molecular librations are sensitive to a so-called dynamical transition in proteins and in other biological systems [ 16 , 19 , 26 , 27 , 28 ], which is known occur between 170 and 220 K from numerous neutron-scattering experiments and MD simulations to—see e.g., [ 29 , 30 , 31 ] for recent references. Note however that the nature of this transition is still heavily debated.…”

Section: Introductionmentioning

confidence: 99%

Evidence for an Ordering Transition near 120 K in an Intrinsically Disordered Protein, Casein

2021

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Intrinsically disordered proteins (IDPs) are proteins that possess large unstructured regions. Their importance is increasingly recognized in biology but their characterization remains a challenging task. We employed field swept Electron Spin Echoes in pulsed EPR to investigate low-temperature stochastic molecular librations in a spin-labeled IDP, casein (the main protein of milk). For comparison, a spin-labeled globular protein, hen egg white lysozyme, is also investigated. For casein these motions were found to start at 100 K while for lysozyme only above 130 K, which was ascribed to a denser and more ordered molecular packing in lysozyme. However, above 120 K, the motions in casein were found to depend on temperature much slower than those in lysozyme. This abrupt change in casein was assigned to an ordering transition in which peptide residues rearrange making the molecular packing more rigid and/or more cohesive. The found features of molecular motions in these two proteins turned out to be very similar to those known for gel-phase lipid bilayers composed of conformationally ordered and conformationally disordered lipids. This analogy with a simpler molecular system may appear helpful for elucidation properties of molecular packing in IDPs.

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Interdigitated lamellar phases in the frozen state: Spin-label CW- and FT-EPR

Cited by 10 publications

References 43 publications

Librational Dynamics of Spin-Labeled Membranes at Cryogenic Temperatures From Echo-Detected ED-EPR Spectra

Librational Dynamics of Spin-Labeled Membranes at Cryogenic Temperatures From Echo-Detected ED-EPR Spectra

Structural properties of supercooled deep eutectic solvents: choline chloride–thiourea compared to reline

Evidence for an Ordering Transition near 120 K in an Intrinsically Disordered Protein, Casein

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