Berlin 2005 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 30: POSTER: Chemical physics
CPP 30.8: Poster
Dienstag, 8. März 2005, 16:30–18:30, Poster TU D
Visualisation, Kinetics, and Thermodynamics of Biomolecular Interactions — •F. Schubert1, H. Zettl1, M. Lysetska1, M. Drechsler2, Y. Talmon3, G. Krauss4, and G. Krausch1 — 1Physikalische Chemie II, Universität Bayreuth, 95440 Bayreuth — 2Makromolekulare Chemie II, Universität Bayreuth, 95440 Bayreuth — 3Department of Chemical Engineering, Technion, Haifa 32000, Israel — 4Laboratorium für Biochemie, Universität Bayreuth, 95440 Bayreuth
We have examined the interactions of DNA and replication protein A (RPA) with atomic force microscopy (AFM), cryo-transmission electron microscopy (cryo-TEM), surface plasmon resonance (SPR), and fluorescence correlation spectroscopy (FCS) to gain a better understanding of structure, kinetics and thermodynamics.
The AFM experiments show a length decrease of the dsDNA upon UV irradiation. Adding RPA to undamaged DNA, only a small amount of complexes with terminal binding can be found. Upon binding of RPA to UV-damaged DNA a length decrease and appearance of globular structures occur. In order to exclude the influence of the mica surface the same experiments were performed using cryo-TEM.
The analysis of SPR and FCS data of ssDNA–RPA interactions includes the determination of the rate constants, the equilibrium constant, and the Gibbs free energy. By performing the reaction at different temperatures, it is possible to extract thermodynamic information about the system. The two methods yield different values for Δ G but almost the same value for Δ H. Thus there has to be a difference in Δ S, which may be due to a different degree of freedom for the DNA.