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BP: Fachverband Biologische Physik

BP 2: Protein Structure \& Dynamics

BP 2.9: Talk

Monday, March 14, 2011, 12:45–13:00, ZEU 260

Water soluble chlorophyll (Chl) binding protein (WSCP) of higher plants as model system for the investigation of pigment-pigment and pigment-protein interactions — •Franz-Josef Schmitt¹, Jörg Pieper², Christoph Theiss¹, Inga Trostmann³, Harald Paulsen³, Thomas Renger⁴, Hans Joachim Eichler¹, Thomas Friedrich¹, and Gernot Renger¹ — ¹Berlin Institute of Technology, Germany — ²University of Tartu, Estonia — ³Johannes Gutenberg University Mainz, Germany — ⁴Johannes Kepler University Linz, Austria

Spectroscopic studies on pigment-pigment and pigment-protein interactions of Chl a and b bound to the recombinant class IIa WSCP from cauliflower are presented. Two Chls form a strongly excitonically coupled open sandwich dimer within the tetrameric protein matrix giving rise to an upper excitonic state with a large oscillator strength.

Fluorescence lifetime measurements show that the unusually high photostability of Chls bound to WSCP most probably originates from a diffusion barrier to interaction of molecular dioxygen with Chl triplets. The spectra are well described by a Chl dimer modulated by the protein environment. These findings are in good agreement with recent hole-burning and fluorescence line narrowing results.

The presented results illustrate the great potential of WSCP as a model system for systematic experimental and theoretical studies on the functionalizing of Chls by the protein matrix. It opens the way for the application of pigment-protein complexes as photo-switchable protein coatings of medical drugs.