Hamburg 2009 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 2: Biomoleküle 1
MO 2.3: Vortrag
Montag, 2. März 2009, 14:30–14:45, VMP 6 HS-F
Ac-AlanLysH+ in vacuo: secondary structure of polyalanine peptides part I — •Frauke Bierau, Peter Kupser, Gert von Helden, Mariana Rossi, Volker Blum, Matthias Scheffler, and Gerard Meijer — Fritz-Haber-Institut, D-14195 Berlin, Germany
For peptides and proteins, IR vibrational spectroscopy on modes that are sensitive to hydrogen bonding is one of the key techniques to investigate the conformational structure. When studying molecules in the gas phase, IR spectra can provide information about intrinsic intramolecular properties, without intermolecular interactions with the environment being present [1].
Polyalanine chains can serve as model systems for helical peptides in the gas phase [2]. IR multiple photon dissociation (IR-MPD) spectroscopy at T= 300 K is performed on Ac-AlanLysH+ (n=5,10,15,19) polypeptides in the spectral range between 1000 and 2000 cm−1, where the amide I (C=O stretching vibration) and amide II (N-H bending vibration) bands are located. The peptides are brought into the gas phase via electrospray ionization (ESI), isolated in a Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometer and irradiated by the free-electron laser FELIX, and the wavelength-dependent change of mass-to-charge is recorded. For the amide I band, a red-shift with increasing chain length is observed. This is in agreement with DFT calculations (part II).
[1] Special issue "Bioactive molecules in the gas phase", PCCP 6 (2004), 2543-2890, [2] Hudgins et al., JACS 120 (1998), 12974.