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Issue 21, 2011
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Phonon-like excitation in secondary and tertiary structure of hydrated protein powders

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Abstract

Existence of sub-thermal collective excitations in proteins is of great interest due to its possible close coupling with the onset of their biological functions. We use high-energy resolution inelastic X-ray scattering to directly measure phonon dispersion relations and their damping in two hydrated proteins, α-chymotrypsinogen A and casein, differing in their secondary and tertiary structures. We observe that specific phonons in the Q range 28–30 nm−1 are markedly softened only above TD = 220 K, the observed protein dynamic transition temperature. This might indicate that only phonon modes within the wavelengths in the length scale comparable to the secondary structure dimension could be linked to the onset of protein biological activity. We also infer that the presence of tertiary structure contributes little to the population of phonons, while the α-helix seems to be the major contributor to phonons propagation.

Graphical abstract: Phonon-like excitation in secondary and tertiary structure of hydrated protein powders

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Publication details

The article was received on 23 May 2011, accepted on 08 Aug 2011 and first published on 06 Sep 2011


Article type: Communication
DOI: 10.1039/C1SM05954H
Citation: Soft Matter, 2011,7, 9848-9853
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    Phonon-like excitation in secondary and tertiary structure of hydrated protein powders

    M. Li, X. Chu, E. Fratini, P. Baglioni, A. Alatas, E. E. Alp and S. Chen, Soft Matter, 2011, 7, 9848
    DOI: 10.1039/C1SM05954H

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