The dynamical transition in proteins of bacterial photosynthetic reaction centers observed by echo-detected EPR of specific spin labels

An echo-detected electron paramagnetic resonance (ED EPR) approach was used to study molecular dynamics in photosynthetic reaction centers (RCs) fromRhodobacter sphaeroides R26, employing the specific spin label methanethiosulfonate and 3-maliemido proxyl. ED EPR has recently been shown to be sensit...

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Bibliographic Details
Published in:Applied magnetic resonance 2007-03, Vol.31 (1-2), p.159-166
Main Authors: Borovykh, I. V., Gast, P., Dzuba, S. A.
Format: Article
Language:English
Subjects:
Anharmonicity
Bacteria
Electron paramagnetic resonance
Electron spin
Electron transfer
Labels
Librational motion
Molecular dynamics
Photosynthesis
Temperature dependence
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Summary:An echo-detected electron paramagnetic resonance (ED EPR) approach was used to study molecular dynamics in photosynthetic reaction centers (RCs) fromRhodobacter sphaeroides R26, employing the specific spin label methanethiosulfonate and 3-maliemido proxyl. ED EPR has recently been shown to be sensitive to so-called dynamical transition in disordered media, which is characterized by the transition from a harmonic-like librational motion of a molecule to an anharmonic one or to a stochastic wobbling motion. ED EPR line shapes studied over a wide temperature range reveal a sharp transition occurring above 180 K. The possible relation of the found transition to the temperature dependence of electron transfer reactions in RC is discussed.
ISSN:0937-9347
1613-7507
DOI:10.1007/BF03166253