# Dresden 2006 – wissenschaftliches Programm

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# CPP: Chemische Physik und Polymerphysik

## CPP 12: POSTER Colloids, Nanoparticles and Self-Organizing Systems

### CPP 12.19: Poster

### Dienstag, 28. März 2006, 17:00–19:00, P3

**Effects of the bead–surface interaction on the restricted rotational dynamics of nonrigid immobilized macromolecules.** — •Alexander Uvarov and Stephan Fritzsche — Universität Kassel, D–34132 Kassel, Germany

Many problems in biophysics involve the rotational motion of macromolecules
which immersed in solution. Well–known examples refere to dielectric relaxation,
nuclear magnetic relaxation as well as to the nd depolarization of the fluorescence light.
During the past decade, therefore, a large number of experiments and
dynamic simulations (DS) have been carried out in order to
describe the rotational properties of biomolecules.
Apart from free macromolecules in solution,
some experiments also concerned the restricted mobility of
macromolecules which are immobilized on a surface and which are interpreted
in terms of their molecular subsystems, the so–called *beads* of the
macromolecule [1].

In the present contribution, we explore the question of how the bead–bead as well as bead–surface interaction affects the (restricted) rotational diffusion of molecules immobilized at a surface. Making use a recently derived Diffusion equation [1], we performed detailed computations for the orientational correlation functions and the rotational diffusion coefficient of the macromolecule for several types of the bead–bead and bead-surface interaction potentials. Results from our theory will be compared with other computations including the Brownian DS of the macromolecule [2].

[1] A. Uvarov and S. Fritzsche, J. Chem. Phys. **121**, 6561, (2004)

[2] B. Carrasco, G. de la Torre, Biophys. Journal **75**, 3044, (1999).