| 1. |
- Dods, Robert, 1989, et al.
(författare)
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Ultrafast structural changes within a photosynthetic reaction centre.
- 2021
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 589:7841, s. 310-314
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthetic reaction centres harvest the energy content of sunlight by transporting electrons across an energy-transducing biological membrane. Here we use time-resolved serial femtosecond crystallography1 using an X-ray free-electron laser2 to observe light-induced structural changes in the photosynthetic reaction centre of Blastochloris viridis on a timescale of picoseconds. Structural perturbations first occur at the special pair of chlorophyll molecules of the photosynthetic reaction centre that are photo-oxidized by light. Electron transfer to the menaquinone acceptor on the opposite side of the membrane induces a movement of this cofactor together with lower amplitude protein rearrangements. These observations reveal how proteins use conformational dynamics to stabilize the charge-separation steps of electron-transfer reactions.
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| 2. |
- Cellini, Andrea, 1991, et al.
(författare)
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The three-dimensional structure of Drosophila melanogaster (6-4) photolyase at room temperature
- 2021
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Ingår i: Acta Crystallographica Section D-Structural Biology. - : International Union of Crystallography (IUCr). - 2059-7983. ; 77, s. 1001-1009
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Tidskriftsartikel (refereegranskat)abstract
- (6-4) photolyases are flavoproteins that belong to the photolyase/cryptochrome family. Their function is to repair DNA lesions using visible light. Here, crystal structures of Drosophila melanogaster (6-4) photolyase [Dm(6-4)photolyase] at room and cryogenic temperatures are reported. The room-temperature structure was solved to 2.27 angstrom resolution and was obtained by serial femtosecond crystallography (SFX) using an X-ray free-electron laser. The crystallization and preparation conditions are also reported. The cryogenic structure was solved to 1.79 angstrom resolution using conventional X-ray crystallography. The structures agree with each other, indicating that the structural information obtained from crystallography at cryogenic temperature also applies at room temperature. Furthermore, UV-Vis absorption spectroscopy confirms that Dm(6-4)photolyase is photoactive in the crystals, giving a green light to time-resolved SFX studies on the protein, which can reveal the structural mechanism of the photoactivated protein in DNA repair.
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| 3. |
- Kübel, Joachim, 1988, et al.
(författare)
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Giving voice to the weak: Application of active noise reduction in transient infrared spectroscopy
- 2021
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 783
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Tidskriftsartikel (refereegranskat)abstract
- The analysis and interpretation of time-resolved spectroscopic data is challenging in the presence of high levels of noise. This problem is particularly common when studying light-activated proteins with transient absorption (TA) spectroscopy. For the same reason, transient 2D-IR remains a notoriously challenging technique that so far has mostly been applied to studying strong oscillators, such as metal carbonyls. Here, we present a detailed implementation of transient 1D and 2D-IR spectroscopy that synchronizes three independent laser sources and applies advanced referencing algorithms for efficient noise suppression. The applied referencing method improves data quality considerably and allows for extracting additional spectroscopic information that is otherwise beyond reach due to very low signal-to-noise ratio. We apply the approach to monitor the complete Pr-to-Pfr transition in the Y263F mutant of a bacterial phytochrome (phi Pr_Pfr < 0.1) covering six orders of magnitude in time, from nanoseconds to milliseconds. We further extend the noise suppression method to transient 2D-IR spectroscopy and conduct a technical feasibility test on a solid-state semiconductor sample (InAs). The presented solutions come at no extra cost when a reference detector is present and are expected to find applications in many spectroscopic studies due to the enhanced ability to detect and interpret very weak signals on multiple timescales.
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