In the cytochrome c oxidase (and other proteins), protons are possibly guided by “antennae” consisting of clusters of negatively charged protein side-chains with overlapping Coulomb cages. To characterize the antenna with its hydration layer, we use electric absorption spectroscopy in the far-infrared and terahertz (THz) range (0.1-200 cm-1). By virtue of this new approach, intermolecular fluctuations of polar residues and solvation water can be observed directly. Overwhelming absorption by bulk water is avoided with the molecular THz probes, small betains which are linked to specific cysteine side-chains; regio-selectivity is made possible by an observation radius of 15 Å.
Gerecke, M., Bierhance, G., Gutmann, M., Ernsting, N.P., and Rosspeintner, A. (2016). Femtosecond broadband fluorescence upconversion spectroscopy: spectral coverage versus efficiency. Review of Scientific Instruments 87, 053115.
Richter, C., Ernsting, N.P., and Mahrwald, R. (2016). Operationally simple and selective one-pot synthesis of hydroxyl-phenones: a facile access to SNARF dyes. Synthesis 48, 1217-1225.
Richter, C., Schneider, C., Quick, M.T., Volz, P., Mahrwald, R., Hughes, J., Dick, B., Alexiev, U., and Ernsting, N.P. (2015). Dual-fluorescence pH probe for bio-labelling. Physical Chemistry Chemical Physics 17, 30590-30597.