Suchergebnisse

Terahertz spectra of four alanine-rich peptides with known secondary structures were studied by terahertz time domain spectroscopy (THz-TDS) and by Fourier transform infrared spectroscopy (FTIR) using a synchrotron light source and a liquid-helium cooled bolometer. At ambient temperatures the usable bandwidth was restricted to 0.2-1.5 THz by the absorbance of water. The existence of a solvation shell around the peptide in solution was observed and its size estimated to be between 11 and 17 Å. By cooling the peptide solution to 80 K in order to reduce the water absorbance the bandwidth was increased to 0.1-3.0 THz for both THz-TDS and FTIR. Spectra were consistent with monotonic absorbance of the peptide and the existence of a solid amorphous low density solvation shell. ; This work was funded by the Australian Research Council grant number DP0773111 and supported by the National Collaborative Research Infrastructure Strategy, an Australian Federal Government initiative. We thank the Australian Synchrotron for access to their infrared beamline (grant numbers FI1137 and FI1437), and Dominique Appadoo and Danielle Martin of the Australian Synchrotron for their assistance. TD thanks the University of Queensland for an international travel grant. JAZ thanks Gonville & Caius College, Cambridge for a Research Fellowship. RL thanks the EPSRC and Trinity College, Cambridge for funding his PhD.