Institut for Biomedicin

Mikael Esmann

Librational fluctuations in protein glasses

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  • Derek Marsh
  • ,
  • Rosa Bartucci
  • ,
  • Rita Guzzi
  • ,
  • Luigi Sportelli
  • ,
  • Mikael Esmann
Librational motions in the region of the protein "glass" (or dynamic) transition are analysed for spin-labelled haemoglobin, serum albumin and β-lactoglobulin by EPR spectroscopy. A discontinuity in the temperature dependence of the mean-square librational amplitude, , occurs in the region of 200K as found for the mean-square atomic displacement, , at the protein dynamic transition by Mössbauer spectroscopy and neutron scattering. The discontinuity in vs. T can be described by the Vogel-Tammann-Fulcher equation, implying a finite glass transition temperature. Above the dynamic transition, vs. 1/T can be approximated by the Arrhenius law with activation energies similar to those usually found for , 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.
TidsskriftBBA General Subjects
Sider (fra-til)1591-1595
Antal sider5
StatusUdgivet - 10 maj 2013

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