How protons migrate via protein-bound water molecules is becoming an emerging research-field in biology, ever since Grotthuss proposed the proton transfer along water chains in liquid water in physical-chemistry. Recent time-resolved FTIR measurements revealed the dynamics of protein-bound water and showed how they can be actively involved in proton transfer using the light-driven proton pump bacteriorhodopsin (bR) as model system (1). The detailed proton transfer via such water molecules involves preordered dangling water, a strong hydrogen-bonded water and most interestingly, a protonated water complex as the proton release group, which we identified for the first time in a protein (2). The central binding site is reprotonated from Asp96 (1). A transient water chain between asp 96 and the central binding site evolves on the milli-second time-scale and the proton is transferred from asp 96 to the central binding site and the pump is reset (4). In summary, the emerging paradigm invokes the principle that protein bound water molecules are as functional as amino acids residues (2).
Furthermore the Ras superfamily and its interaction network is studied by ATR-FTIR spectroscopy.
(1) Gerwert, K., Hess, B., Soppa, J., Oesterhelt, D. PNAS 86, 4943-4947 (1989)
(2) Garczarek, F., Gerwert, K. Nature 439, 109-112 (2006)
(3) Wolf, S., Freier, E., Potschies, M., Hofmann, E. and Gerwert, K.,
Angew. Chem. Int. Ed, 49, 6889-6893 (2010)
(4) Freier, E. Wolff, S. Gerwert, K, , submitted