September 13 - 4:00pm Phys 223
(Coffee at 3:30p.m. in room 242)
Center for Nonlinear Studies Los Alamos National Laboratory
"Ask not what physics can do for biology, ask what biology can do for physics". (Stan Ulam).
Proteins form a unique state of matter, with some properties characteristic of solids, some of liquids, some of polymers, and some of glasses. 4 Gy of evolution have perfected their structure and function. The study of proteins and other biomolecules yields new concepts and new insights into old problems. Possibly the most important concept is that of the energy landscape: Proteins do not have a unique structure and ground state energy; they can assume a very large number of somewhat different structures. This situation is characterized by a rough energy landscape in a space of 3N dimensions, where N is number of atoms in the protein. Each valley in the landscape corresponds to a particular protein conformation, called a conformational substate. The existence of an energy landscape and of substates has been confirmed by many experiments, in particular by a characteristic Debye-Waller factor, nonexponential time dependence of relaxation phenomena, and spectral and kinetic hole burning. One of the main goal of the protein studies is the exploration of the energy landscape, of the laws governing motions in the landscape, and of their connection to structure and function. Preliminary work shows that the landscape is organized in a hierarchy. The dynamics of the motions within the landscape involve molecular tunneling, the effect of friction (Kramers theory), the effect of collective motions, and non-Arrhenius behavior. One ultimate goal of the research is a formulation of the physical laws governing the structure, dynamics, and function of proteins that has predictive power.