Berlin 2014 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 11: Biomolecules 1
MO 11.5: Vortrag
Mittwoch, 19. März 2014, 15:00–15:15, BEBEL HS213
Femtosecond 2D-IR spectroscopy of SCN - a vibrational probe for protein dynamics — •Daniela Kern-Michler, Luuk van Wilderen, Henrike M. Müller-Werkmeister, and Jens Bredenbeck — Institut für Biophysik, Gothe Universität / Frankfurt am Main
Novel vibrational probes like nitrile, azide or thiocyanate (SCN) groups [1] are useful to obtain dynamic and site-specific information in proteins. We measured steady-state and time-resolved infrared (IR) spectra of methylthiocyanate (MeSCN) in various solvents with different polarities and H-bonding character to characterize the SCN moiety as an infrared label. To demonstrate the applicability in a protein, we introduced a S13C15N group into bovine hemoglobin (Hb) [2].The central SCN stretch frequency depends on the solvent properties, making SCN a suitable probe for its local environment. In addition, we measured time-resolved two-dimensional infrared (2D-IR) spectra of S13C15N in Hb, which hint at local structural rearrangements on an ultrafast timescale. The low central frequency observed in the protein compared to MeSCN indicates that the label is not hydrogen bonded, although we measure a shorter vibrational lifetime (T1) than for MeSCN. The rich molecular detail the label provides on its local surroundings, combined with its relatively long T1 (34 ps), makes the SCN vibration thus a promising IR label to resolve protein dynamics.
[1]Lindquist et al. (2009) PCCP,11 (37), 8105-8380 [2] Fafarman et al. (2006). JACS,128, 13356-13357 [3] Kim et al. (2013) Chem. Rev.113 (8), pp 5817-5847