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DY: Fachverband Dynamik und Statistische Physik

DY 2: Statistical physics in biological systems I (joint session DY/BP)

DY 2.4: Vortrag

Montag, 23. März 2009, 11:45–12:00, ZEU 255

Statistical mechanics description of the process of polypeptides and proteins folding — •Alexander Yakubovich, Ilia Solov’yov, Andrey Solov’yov, and Walter Greiner — Frankfurt Institute of Advanced Studies, Goethe—Universität Frankfurt, Ruth-Moufang Straße 1, D-60438 Frankfurt am Main, Germany

The conformational transitions in finite molecular systems, i.e. the transition from a stable 3D molecular structure to a random coil state or vice versa (also known as (un)folding process) occur or can be expected in many different complex molecular systems and in nano objects, such as polypeptides, proteins, polymers, DNA, fullerenes, nanotubes. Experimental studies of the recent years reveal new detailed mechanisms of such nanoscale transitions and challenge the development of new theoretical models for the description of these complex processes. We suggest a theoretical method based on the statistical mechanics for treating the helix↔random coil transition in polypeptides. We consider this process as a first-order phase transition in a finite system and develop a theory which is free of model parameters and is based solely on fundamental physical principles. It describes essential thermodynamical properties of the system such as heat capacity, the phase transition temperature and others from the analysis of the polypeptide potential energy surface calculated as a function of two dihedral angles, responsible for the polypeptide twisting. The developed formalism is extended for the description of helix↔coil transition in solvent. We also provide a recipe for the theoretical description of the folding↔unfolding processes in proteins.