Subpicosecond conformational dynamics of small peptides probed by two-dimensional vibrational spectroscopy

doi:10.1073/pnas.201169498

Subpicosecond conformational dynamics of small peptides probed by two-dimensional vibrational spectroscopy

^†Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin, Germany; and ^§Institute for Physical and Theoretical Chemistry, J. W. Goethe University, Marie-Curie-Strasse 11, D-60439 Frankfurt/Main, Germany

Edited by Robin M. Hochstrasser, University of Pennsylvania, Philadelphia, PA, and approved July 31, 2001 (received for review April 6, 2001)

Abstract

The observation of subpicosecond fluctuations in the conformation of a small peptide in water is demonstrated. We use an experimental method that is specifically sensitive to conformational dynamics taking place on an ultrafast time scale. Complementary molecular-dynamics simulations confirm that the conformational fluctuations exhibit a subpicosecond component, the time scale and amplitude of which agree well with those derived from the experiment.

Footnotes

↵ ‡ Present address: Foundation for Fundamental Research on Matter Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
↵ ¶ To whom reprint requests should be addressed. E-mail: hamm{at}mbi-berlin.de.
This paper was submitted directly (Track II) to the PNAS office.
↵ ‖ The pulse shape at the exit of the Fabry-Perot filter can be approximated as a single-sided exponential convoluted with the shape of the original input pulse. The time-bandwidth product of a single-sided exponential is 1/2ln2π, which is considerably smaller than that of a Gaussian pulse.
Abbreviations:

2D,

two-dimensional;

MD,

molecular dynamics;

NOESY,

nuclear Overhauser effect spectroscopy