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Humboldt-Universität zu Berlin - Institut für Biologie

Biophysikalische Chemie

Portrait AG-Leiter

Prof. Dr. Franz Bartl

The topic of the research group „Biophysical Chemistry“ is the investigation of reaction mechanisms of various photoreceptors with spectroscopic methods, particulary with UV/ Vis and static and time resolved FTIR spectroscopy in the time range from ns to seconds. In order to improve the spectroscopic performance we also develop new advanced spectroscopic techniques. We focus on three types of photoreceptors: Vetrebrate rhodopsin, channelrhodoposins and phytochromes. In the case of vertebrate rhodopsin we concentrate on the light induced activation and deactivation and on the mechanism of G-protein binding, since many severe eye diseases are linked to deviations in these processes caused by mutations of the receptor. Channelrhodopsins are light-gated ion channels that are widely used in optogenetics, since they allow the precise control of neuronal activity by light.

Phytochromes are photoreceptors in plants and bacteria. They are bimodal photoswitches that control important physiological processes such as flowering, greening and seed germination with the potential to control cellular processes by light. An exact understanding of the reaction mechanisms of channelrhodopsins and phytochromes on a molecular level is of utmost biological and medical relevance and the prerequisite for a specific design for optimized optogenetic tools and broader applications.

Another focus of the “Biophysical Chemistry” research group is, in cooperation with the group of Prof. Przybylski (UAM Poznan), the synthesis and biophysical characterization of new derivates of macrolides such as the lactone macrolide - josamycin and the lactam macrolide - rifabutin, which are worldwide used front-line antibiotics. Josamycin as other leucomycins bind to the 50S subunit of the bacterial ribosome and thus inhibit the protein biosynthesis at different stages which is the basis of their antibacterial activity. Our structural studies focus on elucidating the mechanism of action of this new derivatives and we aim to broaden the fields of application and to reduce undesired side effects. On the other hand, these macrolides are very good model systems to study hydrogen bonded networks and proton transfer reactions mediated by water molecules.