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Licensed Unlicensed Requires Authentication Published by De Gruyter (O) April 7, 2011

Femtosecond Coherence Spectroscopic Study of the Onset of Chemical Denaturation of Myoglobin upon Addition of Minor Amounts of Urea

  • Julia Meyer-Ilse , Denis Akimov and Benjamin Dietzek

Abstract

The interaction of urea with myoglobin, as a benchmark system for heme-containing proteins, is studied via femtosecond coherence spectroscopy. The work focuses on the effect of urea on the appearance of low-wavenumber oscillations, which are a measure of the geometrical structure of the heme group and its interaction with the polypeptide chain. Pursuing this approach, structural alterations (i.e. changes in the vibrational dynamics of the heme group) are detected at denaturant concentrations below the full denaturation limit of 6 M urea for myoglobin. In particular, the low-wavenumber oscillation associated with the heme-doming (i.e. the out-off-plane vibration of the propyrin macrocycle) is found to appear spectrally shifted with a concentration of only 3 M urea. These results suggest that the local environment around the heme is already altered despite the fact that macroscopic unfolding as manifested in the thermodynamic properties of the polypeptide chain is not complete at these urea concentrations.


* Correspondence address: Friedrich-Schiller-Univesrität Jena, Institute of Physical Chemistry, Helmholtzweg 4, Abbe Center of Photonics, 07743 Jena, Deutschland,

Published Online: 2011-4-7
Published in Print: 2011-7-1

© by Oldenbourg Wissenschaftsverlag, München, Germany

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