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Biological Water, Protein Structure and the Dynamical Transition

This article explores the concept of the protein dynamical transition in biological water and its relationship with protein structure. It discusses the role of solvent-mediated diffusive motions, the observation of fragile-to-strong dynamic crossover, and the influence of confined geometries on proton dynamics. Molecular dynamics simulations and terahertz dielectric response are used to investigate the causes and characteristics of the dynamical transition.

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Biological Water, Protein Structure and the Dynamical Transition

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  1. Biological Water, Protein Structure and the Dynamical Transition Yunfen He and Andrea Markelz Department of Physics, University at Buffalo, SUNY PRF 39554-AC6 NSF CAREER PHY-0349256

  2. Roh, J.H. et al., Biophys J, (2006) 91, 2573-88. Applying THz to an Outstanding Biomolecular Question The “Protein Dynamical Transition” D. Ringe and G. A. Petsko, Biophysical Chemistry 105 (2003) 667.680 Ribonuclease A The requirement of minimum hydration level suggests the rapid increase in flexibility arises from a change in the dynamics of the solvent in direct contact with the biological molecule, the biological water.

  3. interfacial water & bulk water Samir Kumar Pal and Ahmed H. Zewail, Chemical Reviews, 2004, Vol. 104, No. 4 2099-2123

  4. What is the Dynamical Transition? Solvent mediated diffusive motions: solvent slaved motions • Activated side chain motions • Activated solvent motions • Transition in solvent dynamics

  5. Observation of fragile-to-strong dynamic crossover in protein hydration water S.-H. Chen, L. Liu, E. Fratini, P. Baglioni, A. Faraone, and E. Mamontov Proceedings of National Academy of Sciences of America, 9012–9016 June 13, 2006 103 Strong Glass Fragile Glass

  6. 1BWH.PDB Neutron Scattering Investigations Of Proton Dynamics Of Water And Hydroxyl Species In Confined Geometries S.-H. Chen and C.-K. Loong Nuclear Engineering And Technology, VOL.38 NO.3 APRIL 2006 201-224

  7. ? Does Structure Play a Role in the Dynamical Transition?

  8. Terahertz dielectric response is sensitive to the transition A. Markelz et al. Chemical Physics Letters 442 (2007) 413–417

  9. Solution cell Terahertz Time Domain Spectroscopy (THz TDS)

  10. Net increase in low frequency response with denaturing

  11. Terahertz Dielectric response Herman W. T. van Vlijmen and Martin Karplus, J. Phys. Chem. B 1999, 103, 3009-3021

  12. Protein structure is not necessary for dynamical transition (HEWL)

  13. Protein structure is not necessary for dynamical transition (random coil poly-L-lysine)

  14. Molecular dynamics simulation

  15. Data do not support Fragile to Strong transition • Arrhenius Temperature dependence only • No structural dependence • The dynamical transition is caused by activated diffusive motions!! • Solvent or side chain diffusive motions??

  16. Chain length dependence of dynamical transition

  17. What causes the dynamical transition? • Activated diffusive motions ofadjacent solventresponsible for dynamical transition. • Apparent minimum chain length required for dynamical transition. • The temperature dependence of the diffusive motions is the result of the polypeptide on the dynamics of biological water. • The dynamical transition does not require a protein!!

  18. Thanks & Questions?

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