[MOS] April 17, 2012

[Zina M Queen]

Modern Optics and Spectroscopy

Protein conformational dynamics probed by multidimensional infrared spectroscopy

Kevin Jones,
Massachusetts Institute of Technology
Tuesday, April 17, 2012

12:00-1:00 p.m.
Two dimensional infrared spectroscopy (2D IR), is advantageous for the study of protein and peptide structure and dynamics because it combines ps time resolution with the conformational sensitivity of vibrational spectroscopy and the increased information content provided by multidimensional nonlinear techniques. We have paired amide I 2D IR with a temperature-jump (T-jump) to reveal the nanosecond to millisecond conformational dynamics of two proteins:  the  β-hairpin peptide Trpzip2 (TZ2) and the insulin dimer.  To provide site-specific information, two isotopologues of TZ2 were synthesized to reveal changes in the mid-strand and the β-turn region.  The T-jump reveals two distinct timescales:  a <10 ns solvation response and a 1-2 µs time scale for activated disordering of β-turn structures.  The experimental results are interpreted with spectral modeling of MD simulations, which allows us to kinetically model the shifting conformations of the heterogeneous ensemble.  For insulin, the T-jump induces a dissociation process.  Multiple timescales are observed, suggesting the presence of multiple states.  The observed timescales are attributed to unfolding and dissociation processes.
Grier Room, MIT Bldg 34-401
Refreshments served after the lecture
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