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Journal Article

Librational fluctuations in protein glasses.


Marsh,  D.
Emeritus Group of Spectroscopy and Photochemical Kinetics, MPI for Biophysical Chemistry, Max Planck Society;

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Marsh, D., Barlucci, R., Guzzi, R., Sportelli, L., & Esmann, M. (2013). Librational fluctuations in protein glasses. Biochimica et Biophysica Acta-Proteins and Proteomics, 1834(8), 1591-1595. doi:10.1016/j.bbapap.2013.05.001.

Cite as: https://hdl.handle.net/11858/00-001M-0000-0014-3E9B-6
Librational motions in the region of the protein "glass" (or dynamic) transition are analysed for spin-labelled haemoglobin, serum albumin and beta-lactoglobulin by EPR spectroscopy. A discontinuity in the temperature dependence of the mean-square librational amplitude, <alpha(2)>, occurs in the region of 200 K as found for the mean-square atomic displacement, <r(2)>, at the protein dynamic transition by Mossbauer spectroscopy and neutron scattering. The discontinuity in <alpha(2)> vs. T can be described by the Vogel-Tammann-Fulcher equation, implying a finite glass transition temperature. Above the dynamic transition, <alpha(2)> vs. 1/T can be approximated by the Arrhenius law with activation energies similar to those usually found for <r(2)>, and relaxation processes in glass-forming media and the hydration shells of proteins. Similar results are found for librational fluctuations of membranous Na,K-ATPase spin-labelled either on superficial -SH groups or on those essential to activity.