Glassy dynamics and enzymatic activity of lysozyme.
There has been much interest in the analogies between dynamic processes in proteins and in other complex systems such as viscous liquids and glasses. We have investigated the dynamics of protons along chains of hydrogen-bonded water molecules adsorbed on the surface of the globular protein lysozyme. The hydration dependence of the dielectric relaxation time is fitted by a modified Vogel-Fulcher-Tamman equation, in which the variable temperature has been replaced with hydration. We find that the relaxation time diverges at a singular hydration that coincides with the critical water content required to trigger lysozyme enzymatic activity. This surprising correlation suggests a direct coupling between protein function and glasslike behavior, with possible implications for the turnover number of the enzyme.
Pizzitutti
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Dipartimento di Fisica E. Amaldi, Università di Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy.
Bruni
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D055592:Biophysical Phenomena; D001703:Biophysics; D004563:Electrochemistry; D005898:Glass; D006860:Hydrogen Bonding; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism*; D011522:Protons; D013816:Thermodynamics; D014867:Water
D011522:Protons; D014867:Water; D009113:Muramidase