In this reporting period, papers dealing with the following projects appeared in print: (1) Reaction dynamics on a thermally fluctuating potential; (2) Theory of the fluorescence of singlymolecules undergoing multistate conformational dynamics; (3) Asimple model for protein folding that illustrates a large numberof concepts needed to understand this process, including entropic barriers, transition states, funnels and the origin of single exponential folding kinetics. The first paper deals with the important problem of how fluctuations in the environment, such as those that occur in the active site of an enzyme, influence the rate of a chemical reaction. The second paper addresses the problem of how one should interpret recent and novel fluorescence experiments not on bulk samples but on individual molecules. The third paper introduces the simplest model that captures themost fundamental aspect of protein folding, namely that both the entropy (that is the number of configurations) and the energy decrease as folding occurs. This is in contrast to most chemical reactions where bonds are first broken, leading to an increase in energy. The interesting finding is that this """"""""bare bones""""""""model is able to account for a surprising number of experimental trends, showing how such results follow from the simplest physical assumptions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Intramural Research (Z01)
Project #
1Z01DK029019-20
Application #
6432088
Study Section
(LCP)
Project Start
Project End
Budget Start
Budget End
Support Year
20
Fiscal Year
2000
Total Cost
Indirect Cost
Name
U.S. National Inst Diabetes/Digst/Kidney
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Berezhkovskii, Alexander; Hummer, Gerhard; Szabo, Attila (2009) Reactive flux and folding pathways in network models of coarse-grained protein dynamics. J Chem Phys 130:205102
Gopich, Irina V; Nettels, Daniel; Schuler, Benjamin et al. (2009) Protein dynamics from single-molecule fluorescence intensity correlation functions. J Chem Phys 131:095102
Bezrukov, Sergey M; Berezhkovskii, Alexander M; Szabo, Attila (2007) Diffusion model of solute dynamics in a membrane channel: mapping onto the two-site model and optimizing the flux. J Chem Phys 127:115101
Dudko, Olga K; Mathe, Jerome; Szabo, Attila et al. (2007) Extracting kinetics from single-molecule force spectroscopy: nanopore unzipping of DNA hairpins. Biophys J 92:4188-95
Berezhkovskii, Alexander; Szabo, Attila (2006) Perturbation theory of Phi-value analysis of two-state protein folding: relation between p fold and Phi values. J Chem Phys 125:104902
Dudko, Olga K; Hummer, Gerhard; Szabo, Attila (2006) Intrinsic rates and activation free energies from single-molecule pulling experiments. Phys Rev Lett 96:108101
Gopich, Irina; Szabo, Attila (2005) Fluorophore-quencher distance correlation functions from single-molecule photon arrival trajectories. J Phys Chem B 109:6845-8
Berezhkovskii, Alexander; Szabo, Attila (2005) One-dimensional reaction coordinates for diffusive activated rate processes in many dimensions. J Chem Phys 122:14503
Gopich, Irina V; Szabo, Attila (2005) Photon counting histograms for diffusing fluorophores. J Phys Chem B 109:17683-8
Gopich, Irina; Szabo, Attila (2005) Theory of photon statistics in single-molecule Forster resonance energy transfer. J Chem Phys 122:14707

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