Visualizing Photochemical Dynamics in Solution through Picosecond X-Ray Scattering

Neutze, Richard; Wouts, R.; Techert, Simone; Davidsson, Jan; Kocsis, M.; Kirrander, Adam; Schotte, Friedrich; Wulff, Michaël

doi:10.1103/physrevlett.87.195508

Cited by 111 publications

(90 citation statements)

References 33 publications

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“…New x-ray free electron laser facilities, including LCLS [2], XFEL [3], SACLA [4], and FERMI [5], capable of short duration, tunable wave length x-ray pulses with high photon flux, will provide powerful tools for the imaging of matter, including ultrafast x-ray diffraction with spatial and temporal resolution [6,7]. Time-resolved x-ray diffraction capable of imaging atomic motion has already been demonstrated at third generation synchrotrons [8][9][10] for comparatively slow processes. Recently, diffraction from nanocrystals [11] and noncrystalline biological samples [12], as well as from isolated and strongly aligned gas phase molecules [13], has been observed using x-ray pulses at the LCLS.…”

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How to Observe Coherent Electron Dynamics Directly

Suominen

Kirrander

2014

Phys. Rev. Lett.

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Detection of electron motion by elastic scattering of short x-ray pulses from a coherent superposition of highly excited electronic states in rare gas atoms is investigated. The laser excitation of the electron wave packet introduces strong anisotropy which facilitates detection, and large differences in the radial distribution of the excited Rydberg and core electrons allow the dynamics to be detected using both soft and hard x rays.

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How to Observe Coherent Electron Dynamics Directly

Suominen

Kirrander

2014

Phys. Rev. Lett.

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“…The method has been applied to follow chemical reactions of small molecules (29)(30)(31) as well as structural dynamics of photoactive proteins (32-41).…”

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Ultrafast anisotropic protein quake propagation after CO photodissociation in myoglobin

Brinkmann

Hub

2016

Proc. Natl. Acad. Sci. U.S.A.

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"Protein quake" denotes the dissipation of excess energy across a protein, in response to a local perturbation such as the breaking of a chemical bond or the absorption of a photon. Femtosecond timeresolved small-and wide-angle X-ray scattering (TR-SWAXS) is capable of tracking such ultrafast protein dynamics. However, because the structural interpretation of the experiments is complicated, a molecular picture of protein quakes has remained elusive. In addition, new questions arose from recent TR-SWAXS data that were interpreted as underdamped oscillations of an entire protein, thus challenging the long-standing concept of overdamped global protein dynamics. Based on molecular-dynamics simulations, we present a detailed molecular movie of the protein quake after carbon monoxide (CO) photodissociation in myoglobin. The simulations suggest that the protein quake is characterized by a single pressure peak that propagates anisotropically within 500 fs across the protein and further into the solvent. By computing TR-SWAXS patterns from the simulations, we could interpret features in the reciprocalspace SWAXS signals as specific real-space dynamics, such as CO displacement and pressure wave propagation. Remarkably, we found that the small-angle data primarily detect modulations of the solvent density but not oscillations of the bare protein, thereby reconciling recent TR-SWAXS experiments with the notion of overdamped global protein dynamics.time-resolved SAXS/WAXS | free-electron laser | molecular dynamics F unctional protein dynamics occur on various timescales, ranging from tens of femtoseconds for bond breaking, up to milliseconds and seconds for large-scale conformational transitions or protein folding. Observing and explaining such transitions, if possible in a time-resolved manner, has remained a central goal of molecular biophysics. A popular model system used to study proteins dynamics has been the 18-kDa protein myoglobin (Mb), the protein of first known tertiary structure (1). Mb contains an iron-porphyrin heme group that reversibly binds small gas molecules such as molecular oxygen (O 2 ) or carbon monoxide (CO). Mb is abundant in the muscle tissue of vertebrates, where it plays an important role in the transport and storage of O 2 and in the biochemistry of nitric oxide (2, 3).Because the CO-iron bonds in a Mb ensemble can be coherently photolysed with a laser flash within only 50 fs (4), a range of time-resolved techniques has been applied to probe various aspects of the structural dynamics after CO photodissociation, such as energy dissipation, CO dynamics, or heme doming (5-15). Three-dimensional movies of Mb conformational transitions were derived by means of time-resolved crystallography, which recently reached subpicosecond time resolution (16-19). These experimental studies were complemented by several pioneering molecular-dynamics (MD) simulations that revealed the Mb dynamics with atomic detail, with some focus on heat dissipation, vibrational dynamics, as well as ligand migration (20-28).Time-re...

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“…Non-thermal melting of semiconductor [1][2][3], dynamics of acoustic and optical phonons [4][5][6][7][8] as well as ferroelectric phase-transitions [9][10] and nanostructured materials have been investigated [11][12]. Probing chemical reactions, with diffraction or X-ray absorption spectroscopy [13][14] and the study of the dynamics of photo-excited biomolecules [15][16] are examples of time-resolved X-ray techniques applied outside the physical sciences. New methods in structural determination will also require bright, short-pulse sources [17] The next quantum leap in source technology will be taken when the hard X-ray SASE-FEL (Selfamplified spontaneous emission free electron laser) at SLAC Stanford becomes operational in 2009 [18].…”

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confidence: 99%