Molecular dynamics of nitroxides in glasses as studied by multi-frequency EPR

Kirilina, Evgeniya; Prisner, Thomas F.; Bennati, Marina; Endeward, Burkhard; Dzuba, Sergei A.; Fuchs, Martin R.; Möbius, K.; Schnegg, Alexander

doi:10.1002/mrc.1677

Cited by 28 publications

(17 citation statements)

References 42 publications

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“…A number of independent physical approaches including Mössbauer, fluorescence, phosphorescence spectroscopic methods, advance pulse and multi‐frequency ESR and nuclear magnetic resonance (NMR) confirmed main conclusions about low temperature dynamic behavior of the liquid and glassy objects obtained by the nitroxide and fluorescence‐nitroxide spin probe method (3,21,25,26).…”

Section: Molecular Dynamics Probesmentioning

confidence: 64%

Dual Chromophore‐Nitroxides: Novel Molecular Probes, Photochemical and Photophysical Models and Magnetic Materials

Likhtenstein

Ishii

Nakatsuji

2007

Photochem & Photobiology

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Over the last decades scientists have faced growing requirements in novel methods of fast and sensitive analysis of antioxidant status of biological systems, spin redox probing and spin trapping, investigation of molecular dynamics, and of convenient models for studies of photophysical and photochemical processes. In approaching this problem, methods based upon the use of dual chromophore-nitroxide (CN) compounds have been suggested and developed. A CN consists of two molecular sub-functionality (a chromophore and a stable nitroxide radical) tethered together by spacers. In the dual compound the nitroxide is a strong intramolecular quencher of the fluorescence from the chromophore fragment. Reduction to hydroxylamine, oxidation of the nitroxide fragment or addition of an active radical yield the fluorescence increase and the parallel decay of the fragment electron spin resonance (ESR) signal. At certain conditions the dual molecules undergo photomagnetic switching and form excited state multi-spin systems. These unique properties of CN were intensively exploited as the basis for several methodologies, which include molecular probing, modeling intramolecular photochemical and photophysical processes, and construction of new magnetic materials.

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Section: Molecular Dynamics Probesmentioning

confidence: 64%

Dual Chromophore‐Nitroxides: Novel Molecular Probes, Photochemical and Photophysical Models and Magnetic Materials

Likhtenstein

Ishii

Nakatsuji

2007

Photochem & Photobiology

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“…As is well known, magnetic resonance spectroscopy can not only probe the static structural details of a molecule but also details of its dynamic properties [80][81][82]. If the motion is on the time scale of the EPR experiment, spin relaxation and, thereby, line broadening can be observed in the cw EPR spectrum.…”

Section: Conformational Cofactor Dynamicsmentioning

confidence: 97%

The Magic of Disaccharide Glass Matrices for Protein Function as Decoded by High-Field EPR and FTIR Spectroscopy

et al. 2015

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The structural and dynamical interaction of proteins with their microenvironment in disordered matrices plays a decisive role for their function; EPR spectroscopy is a powerful tool for shading light onto the molecular mechanisms of this protein-matrix interplay. To clarify the molecular mechanisms of disaccharide bioprotection, we studied the structure and dynamics of spin-labeled systems and photosynthetic reaction centers (RCs) in sucrose and trehalose matrices at different hydration levels by means of cw and pulse high-field 95 GHz (W-band) EPR as well as by FTIR. In this minireview, we summarize and discuss EPR and FTIR experiments showing that the anhydrobiotic state of the RC-trehalose system (1) is not the result of matrix-induced changes of the local structure of the charge-separated radical-pair cofactors, P Áþ 865 and Q ÁÀ A , and (2) is not the result of changes of local dynamics and local hydrogen bonding of Q A in its binding pocket. Rather, the extreme impairment of RC dynamics caused by incorporation into the dehydrated trehalose matrix, which also protects it against thermal denaturation, originates in the high rigidity, already at room temperature, of the dry trehalose glass matrix coating the RC protein surface. This surface hydrogen-bonding scaffold shifts the correlation time of thermal conformational fluctuations into the non-biological time domain. Another intriguing aspect of disaccharide bioprotection is the superior The authors dedicate this work to Giovanni Giacometti on the occasion of his 85th birthday. AppliedMagnetic Resonance efficiency of trehalose versus sucrose matrices in stabilizing the anhydrobiotic state of proteins. To clarify the molecular basis of this specificity, glassy trehalose-water and sucrose-water binary systems, incorporating a nitroxide radical as spin probe, have been studied by high-field W-band EPR spectroscopy at different water contents. Analysis of the EPR spectra revealed a different structural and dynamical organization in the sucrose and trehalose matrix, only the trehalose being homogeneous in terms of residual water and nitroxide distribution.

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“…At W-band and higher frequencies, the state-of-the-art in terms of minimum detectable number of spins and shortest p-pulse length is given by the cylindrical metallic cavity operating in the TE 011 mode [3][4][5][6][7][8][9][10][11][12][13]. The basic structure of the cavity is represented by a cylindrical volume delimited by metallic walls and plungers [14].…”

Section: Introductionmentioning

confidence: 99%