A broad glass transition in hydrated proteins.
We performed Raman and Brillouin scattering measurements to estimate glass transition temperature, T(g), of hydrated protein. The measurements reveal very broad glass transition in hydrated lysozyme with approximate T(g) approximately 180+/-15 K. This result agrees with a broad range of T(g) approximately 160-200 K reported in literature for hydrated globular proteins and stresses the difference between behavior of hydrated biomolecules and simple glass-forming systems. Moreover, the main structural relaxation of the hydrated protein system that freezes at T(g) approximately 180 K remains unknown. We emphasize the difference between the "dynamic transition", known as a sharp rise in mean-squared atomic displacement <r(2)> at temperatures around T(D) approximately 200-230 K, and the glass transition. They have different physical origin and should not be confused.
Khodadadi
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Department of Polymer Science, University of Akron, Akron, OH 44325, USA.
Malkovskiy
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Kisliuk
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Sokolov
A P
AP
D009113:Muramidase / Q000737:chemistry; D044367:Phase Transition; D011506:Proteins / Q000737:chemistry*; D012542:Scattering, Radiation; D013059:Spectrum Analysis, Raman; D013696:Temperature; D014867:Water / Q000737:chemistry*
D011506:Proteins; D014867:Water; D009113:Muramidase