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- Andreoni, Alessio, et al.
(författare)
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Fluorescence Correlation Spectroscopy of Labeled Azurin Reveals Photoinduced Electron Transfer between Label and Cu Center
- 2018
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Ingår i: Chemistry - A European Journal. - : WILEY-V C H VERLAG GMBH. - 0947-6539 .- 1521-3765. ; 24:3, s. 646-654
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescent labeling of biomacromolecules enjoys increasing popularity for structural, mechanistic, and microscopic investigations. Its success hinges on the ability of the dye to alternate between bright and dark states. Forster resonance energy transfer (FRET) is an important source of fluorescence modulation. Photo-induced electron transfer (PET) may occur as well, but is often considered only when donor and acceptor are in van der Waals contact. In this study, PET is shown between a label and redox centers in oxidoreductases, which may occur over large distances. In the small blue copper protein azurin, labeled with ATTO655, PET is observed when the label is at 18.5 angstrom, but not when it is at 29.1 angstrom from the Cu. For Cu-II, PET from label to Cu occurs at a rate of (4.8 +/- 0.3) x 10(4) s(-1) and back at (0.7 +/- 0.1) x 10(3) s(-1). With Cu-I the numbers are (3.3 +/- 0.7) x 10(6) s(-1) and (1.0 +/- 0.1) x 10(4) s(-1). Reorganization energies and electronic coupling elements are in the range of 0.8-1.2 eV and 0.02-0.5 cm(-1), respectively. These data are compatible with electron transfer (ET) along a through-bond pathway although transient complex formation followed by ET cannot be ruled out. The outcome of this study is a useful guideline for experimental designs in which oxidoreductases are labelled with fluorescent dyes, with particular attention to single molecule investigations. The labelling position for FRET can be optimized to avoid reactions like PET by evaluating the structure and thermodynamics of protein and label.
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| 2. |
- Panman, Matthijs R, 1983, et al.
(författare)
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Transient two-dimensional vibrational spectroscopy of an operating molecular machine
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Synthetic molecular machines are promising building blocks for future nanoscopic devices. However, the details of their mechanical behaviour are in many cases still largely unknown. A deeper understanding of mechanics at the molecular level is essential for the design and construction of complex nanodevices. Here, we show that transient two-dimensional infrared (T2DIR) spectroscopy makes it possible to monitor the conformational changes of a translational molecular machine during its operation. Translation of a macrocyclic ring from one station to another on a molecular thread is initiated by a UV pulse. The arrival of the shuttling macrocycle at the final station is visible from a newly appearing cross peak between these two moieties. To eliminate spectral congestion in the T2DIR spectra, we use a subtraction method applicable to many other complex molecular systems. The T2DIR spectra indicate that the macrocycle adopts a boat-like conformation at the final station, which contrasts with the chair-like conformation at the initial station. © 2017 The Author(s).
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| 3. |
- Pfeifer, L., et al.
(författare)
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Controlling forward and backward rotary molecular motion on demand
- 2022
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Synthetic molecular machines hold tremendous potential to revolutionize chemical and materials sciences. Their autonomous motion controlled by external stimuli allows to develop smart materials whose properties can be adapted on command. For the realisation of more complex molecular machines, it is crucial to design building blocks whose properties can be controlled by multiple orthogonal stimuli. A major challenge is to reversibly switch from forward to backward and again forward light-driven rotary motion using external stimuli. Here we report a push-pull substituted photo-responsive overcrowded alkene whose function can be toggled between that of a unidirectional 2(nd) generation rotary motor and a molecular switch depending on its protonation and the polarity of its environment. With its simplicity in design, easy preparation, outstanding stability and orthogonal control of distinct forward and backward motions, we believe that the present concept paves the way for creating more advanced molecular machines. Being able to control motion at the molecular level is vital for many future developments in the molecular sciences. Here, the authors report the controlled forward and backward rotation of a molecular motor guided by external stimuli.
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