Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Posters: Protein structure and dynamics

BP 17.18: Poster

Monday, March 16, 2015, 17:30–19:30, Poster A

Rate equations as a tool for kinetic modelling of iRFP’s — •Mario Willoweit, Nico Herder, Luisa Sauthof, Neslihan Tavraz, Franz-Josef Schmitt, and Thomas Friedrich — Institute of Chemistry, Bioenergetics, Technical University Berlin, Germany

Recent developments in protein design led to a near infrared fluorescent protein (iRFP) based on a bacteriophytochrome RpBphP2 (P2). Switchable infrared fluorescent probes with enhanced fluorescence quantum yield are required for modern microscopic applications like IR fluorescence microscopy. We investigated low-temperature time- and wavelength-correlated single photon counting in the wide temperature range from 10 K to 300 K to monitor chromophore-protein interactions. A rate equation model assuming ground state heterogeneity and three excited states: PR*, pre-Lumi-R* and Lumi-R* leads to the corresponding temperature-dependent rate constants and therefore a better understanding of the underlying pigment-protein coupling and the apparent fluorescent states in the system. The results enable to identify the molecular determinants for the fluorescence enhancement of iRFP compared to the wild-type protein. It is suggested that the mutations P2 D202T and P2 Y258F are mainly responsible for enhanced fluorescence quantum yield.