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Some like it cool –
THz absorption studies of as a tool to study biomolecular hydration
Martina Havenith
Ruhr-Universität Bochum
The details of hydration still raise fundamental questions relevant to a large variety of
problems in chemistry and biology. We have shown the THz spectroscopy in combination
with MD simulations is a powerful took to study the sub-nsec hydration.
THz spectroscopy is also able to reveal the important role of hydration on biomolecular
function: Antifreeze proteins (AFPs) are specific proteins which are able to lower the freezing
point of aqueous solutions relative to the melting point. They are preferential docking to ice
nano ice crystals thereby preventing further growth of these. Whereas the antifreeze acitivity
for several of these AFP has been characterized so far, the molecular mechanism is still a
matter of controversial discussion:
By a combination of THz absorption spectroscopy and MD simulations we could show that
the activity of AFPs can be attributed to two distinct molecular mechanisms: a) short range
direct interaction of the protein surface with the growing ice face and b) long range interaction
via protein-induced water dynamics extending up to 20 Å from the protein surface. We
propose a long range retardation of the H-bond dynamics with a gradient towards the ice
binding site. A similar gradient in the H-bond dynamics was found by us for enzymes near the
catalytic site. We will discuss the underlying molecular mechanism supporting the docking at
specific sites.
References:
M. Heyden, E. Bründermann, U. Heugen, G. Niehues, D.M. Leitner, M. Havenith, Long range
influence of carbohydrates on the solvation dynamics of water – Answers from THz absorption
measurements and molecular modeling simulations, J. Am. Chem. Soc. 130, 5773-5779 (2008)
M. Grossmann, B. Born, M. Heyden, D. Tworowski, G.B. Fields, I. Sagi, M. Havenith, Correlated
structural kinetics and retarded solvent dynamics at the metalloprotease active site, Nature
Structural & Molecular Biology 18, 1102-1108 (2011).
S. Funkner, G. Niehues, D.A. Schmidt, M. Heyden, G. Schwaab, K.M. Callahan, D.J. Tobias,
M. Havenith, Watching the low frequency motions in aqueous salt solutions – the terahertz
vibrational signatures of hydrated ions, JACS, 134, 1030-1035 (2012).
K. Meister, S. Ebbinghaus, Y. Xu, J.G. Duman, A. DeVries, M. Gruebele, D.M. Leitner,
M. Havenith, Long-range protein-water dynamics in hyperactive insect antifreeze proteins, Proc.
Natl. Acad. Sci. USA 110(5) 1617-1622 (2013).