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Permanent URI for this collectionhttps://gupea-staging.ub.gu.se/handle/2077/85452

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    Bacteriorhodopsin: structural insights revealed using X-ray lasers and synchrotron radiation
    (2019) Wickstrand, Cecilia; Nogly, Przemyslaw; Nango, Eriko; Iwata, So; Standfuss, Jörg; Neutze, Richard
    2 Abstract: Directional transport of protons across an energy transducing membrane, or “proton pumping”, is ubiquitous in biology. Bacteriorhodopsin is a light-driven proton pump that is activated by a buried all-trans retinal chromophore being photo-isomerized to a 13-cis conformation. The mechanism by which photo-isomerization initiates directional proton transport against a proton concentration gradient has been studied by a myriad of biochemical, biophysical and structural techniques. X-ray free electron lasers (XFELs) have created new opportunities to probe the structural dynamics of bacteriorhodopsin at room temperature on time-scales from femtoseconds to milliseconds using time-resolved serial femtosecond crystallography (TRSFX). We review these recent developments and highlight where XFEL studies reveal new details concerning the structural mechanism of retinal photo-isomerization and proton pumping. We also discuss the extent to which these insights were anticipated by earlier intermediate trapping studies using synchrotron radiation. We believe that TR-SFX will open up the field for dynamical studies of other proteins that are not naturally light-sensitive.
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    Spatiotemporal Release of Singlet Oxygen in Low Molecular Weight Organo-Gels Upon Thermal or Photochemical External Stimuli
    (Wiley, 2024) Sandelin, Emil; Schilling, Leonard; Saha, Ekata; Ruiu, Andrea; Neutze, Richard; Sundé, Henrik; Wallentin, Carl-Johan
    The first example of a material capable of spatiotemporal catch and release of singlet oxygen (1O2) in gel phase is presented. Several low molecular weight organogelators based around an oxotriphenylhexanoate (OTHO) core are developed and optimized with regard to; their gelation properties, and ability of releasing 1O2 upon thermal and/or photochemical external stimuli, in both gel phase and solution. Remarkably, reversible phase transitioning between the gel and solution phase are also demonstrated. Taken together two complementary modes of releasing 1O2, one thermally controlled over time, and one rapid release by means of photochemical stimuli is disclosed. These findings represent the first phase reversible system where function and aggregation properties can be controlled independently, and thus pave the way for novel applications in material sciences as well as in life sciences.