TITLE: "New Algorithms and the Statistical Physics of Protein Folding"

SPEAKER: Professor Ulrich H. E. Hansmann,

TIME: Thursday Feb. 8, 2001 at 4 PM

PLACE: George P. Williams, Jr. Lecture Hall, (Olin 101)

The protein-folding problem is to understand for a given protein the relation between its sequence of amino acids and the set of thermally accessible conformations; and to comprehend the mechanism by which the protein folds into its biologically active structure.

In principle, such questions can be studied by computer simulations. However, the energy landscape of proteins is characterized by a multitude of local minima separated by high energy barriers. Hence, low temperature simulations by canonical molecular dynamics or Monte Carlo will get trapped in configurations corresponding to one of these local minima. We show how this so-called multiple-minima problem can be overcome by new simulation techniques such as parallel tempering and generalized-ensemble algorithms.

We demonstrate the effectiveness of this approach for protein simulations, and study these molecules from a statistical physics point of view. The free energy landscape and structural transitions in small proteins are evaluated. For some homopolymers, a set of critical exponents is calculated which characterizes the helix-coil transition.

References

1. U. H. E. Hansmann and Y. Okamoto, in Annual Reviews in Computational Physics VI. Edited by Stauffer D., Singapore: World Scientific; (1999) 129.
2. U. H. E. Hansmann, Y. Okamoto and J. N. Onuchic, Proteins 34 (1999) 472.
3. U. H. E. Hansmann Eur. Phy. J. B, 12 (1999) 607; N. A. Alves and U. H. E. Hansmann, Int. J. Mod. Phys. C, 11 (2000) 301.
4. N. A. Alves and U. H. E. Hansmann, Phys. Rev. Let., 84 (2000) 1836.