Cluster of Excellence, University of Freiburg

Lipid-Protein interactions in Signalling

Prof. Dr. Heiko Heerklotz (CIBSS-AI), Department of Pharmaceutical Technology and Biopharmacy (Faculty of Chemistry and Pharmacy), University of Freiburg

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Time correlated single photon counting (TCSPC) is a very powerful, subnanosecond time-resolved fluorescence technique to study interactions, structures, and dynamics in biological systems in great detail. Experimental approaches include time-resolved emission spectra (characterizing in detail dipolar relaxation phenomena), polarization (describing angular motion and its possible limitations), Förster resonance energy transfer (specifying distances on the sub-nm and nm scale), and dynamic quenching. A drawback of all these techniques used to be that fluorescent labels have to be added to the molecules of interest, which might severely interfere with the behaviour of these molecules and hence, bias the results. The intrinsic fluorophores of proteins and peptides, Trp and Tyr, could not be excited with sources of sufficient intensity and narrow pulse width to pursue most of these TCSPC techniques so far. Our project enables us to purchase a revolutionary laser system that, for the first time, will open these avenues of research. On this basis, we will establish techniques that help characterizing protein-lipid interactions and their relevance for membrane signaling. As part of the study of signaling events across scales, these techniques shed light also on (sub-) nanosecond and nanometer scaled phenomena.