"Infrared studies of small azobenzene peptides - unexpectedly slow reactions on the time range of minutes"Florian O. Koller, Rossana Reho, Tobias E. Schrader, Luis Moroder, Josef Wachtveitl, Wolfgang Zinth
Journal of Physical Chemistry B, 111 (2007) 10481-10486
Infrared (IR) absorption experiments on light triggered azobenzene peptides have been performed below and above the freezing point of the solvent dimethyl-sulfoxide (DMSO). Even 20 K below the freezing point illumination of the azobenzene chromophore resulted in IR absorption changes indicative for light induced structural rearrangements of the peptide. In addition, new conformational states could be found at low temperature, which involve the formation of additional hydrogen bonds. In one sample the new low temperature state survived melting and reheating and disappeared at 298 K only on the time scale of 10 minutes. The observations indicate that at low temperatures the peptide together with traces of water, present in the sample, forms a shell in the vicinity of the chromophore which facilitates internal motion even in the rigid cage of frozen DMSO.
BMO authors (in alphabetic order):
Peptide and protein folding
Photoswitchable model peptides and their conformational dynamics