Regensburg 2019 – scientific programme

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BP: Fachverband Biologische Physik

BP 3: Bioimaging and biospectroscopy I

BP 3.4: Talk

Monday, April 1, 2019, 10:15–10:30, H11

Photoinduced processes of free bilins in solution: Femtosecond transient absorption spectroscopy on phycocyanobilin — •Maximilian Theiß¹, Tilman Lamparter², Maria Andrea Mroginski³, Jörg Matysik⁴, Chen Song⁴, Wolfgang Gärtner⁴, and Rolf Diller¹ — ¹TU Kaiserslautern, D-67663 Kaiserslautern — ²KIT, D-76131 Karlsruhe — ³TU Berlin, D-10623 Berlin — ⁴Universität Leipzig, D-04103 Leipzig

Bilins are linear tetrapyrroles with rich photochemistry in solution (1,2). When bound to proteins they serve as chromophore in plant-phytochromes, bacterial sensor proteins and optogenetic systems (3). In the bound form protein-chromophore interaction restricts the potentially possible degrees of freedom (4). For a better understanding of the underlying mechanisms we study the primary photochemistry of the free bilin phycocyanobilin (PCB), employing fs transient absorption in the UV/Vis and mid-IR spectral region, complemented by quantum chemical calculations, static fluorescence and NMR measurements. In particular, PCB consists of different ground state species and shows photoinduced conformational changes (5) as well as alteration of protonation state. Additionally, broad IR continuum absorption bands in the transient absorption spectra indicate an ultrafast proton release reaction.

(1) Falk. (2012) The chemistry of linear oligopyrroles and bile pigments. SSBM. (2) Carreira-Blanco et al. (2016) PCCP 18:7148. (3) Gasser et al. (2014) PNAS 111.24:8803. (4) Singer et al. (2016) CPC 17:1288. (5) Dietzek et al. (2011) CPL 515:163.