45
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Proteins in Action: Femtosecond to Millisecond Structural Dynamics of a Photoactive Flavoprotein

      research-article

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Living systems are fundamentally dependent on the ability of proteins to respond to external stimuli. The mechanism, the underlying structural dynamics, and the time scales for regulation of this response are central questions in biochemistry. Here we probe the structural dynamics of the BLUF domain found in several photoactive flavoproteins, which is responsible for light activated functions as diverse as phototaxis and gene regulation. Measurements have been made over 10 decades of time (from 100 fs to 1 ms) using transient vibrational spectroscopy. Chromophore (flavin ring) localized dynamics occur on the pico- to nanosecond time scale, while subsequent protein structural reorganization is observed over microseconds. Multiple time scales are observed for the dynamics associated with different vibrations of the protein, suggesting an underlying hierarchical relaxation pathway. Structural evolution in residues directly H-bonded to the chromophore takes place more slowly than changes in more remote residues. However, a point mutation which suppresses biological function is shown to ‘short circuit’ this structural relaxation pathway, suppressing the changes which occur further away from the chromophore while accelerating dynamics close to it.

          Related collections

          Most cited references34

          • Record: found
          • Abstract: found
          • Article: found
          Is Open Access

          Rapid planetesimal formation in turbulent circumstellar discs

          The initial stages of planet formation in circumstellar gas discs proceed via dust grains that collide and build up larger and larger bodies (Safronov 1969). How this process continues from metre-sized boulders to kilometre-scale planetesimals is a major unsolved problem (Dominik et al. 2007): boulders stick together poorly (Benz 2000), and spiral into the protostar in a few hundred orbits due to a head wind from the slower rotating gas (Weidenschilling 1977). Gravitational collapse of the solid component has been suggested to overcome this barrier (Safronov 1969, Goldreich & Ward 1973, Youdin & Shu 2002). Even low levels of turbulence, however, inhibit sedimentation of solids to a sufficiently dense midplane layer (Weidenschilling & Cuzzi 1993, Dominik et al. 2007), but turbulence must be present to explain observed gas accretion in protostellar discs (Hartmann 1998). Here we report the discovery of efficient gravitational collapse of boulders in locally overdense regions in the midplane. The boulders concentrate initially in transient high pressures in the turbulent gas (Johansen, Klahr, & Henning 2006), and these concentrations are augmented a further order of magnitude by a streaming instability (Youdin & Goodman 2005, Johansen, Henning, & Klahr 2006, Johansen & Youdin 2007) driven by the relative flow of gas and solids. We find that gravitationally bound clusters form with masses comparable to dwarf planets and containing a distribution of boulder sizes. Gravitational collapse happens much faster than radial drift, offering a possible path to planetesimal formation in accreting circumstellar discs.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Versatile Photocatalytic Systems for H2 Generation in Water Based on an Efficient DuBois-Type Nickel Catalyst

            The generation of renewable H2 through an efficient photochemical route requires photoinduced electron transfer (ET) from a light harvester to an efficient electrocatalyst in water. Here, we report on a molecular H2 evolution catalyst (NiP) with a DuBois-type [Ni(P2 R′N2 R″)2]2+ core (P2 R′N2 R″ = bis(1,5-R′-diphospha-3,7-R″-diazacyclooctane), which contains an outer coordination sphere with phosphonic acid groups. The latter functionality allows for good solubility in water and immobilization on metal oxide semiconductors. Electrochemical studies confirm that NiP is a highly active electrocatalyst in aqueous electrolyte solution (overpotential of approximately 200 mV at pH 4.5 with a Faradaic yield of 85 ± 4%). Photocatalytic experiments and investigations on the ET kinetics were carried out in combination with a phosphonated Ru(II) tris(bipyridine) dye (RuP) in homogeneous and heterogeneous environments. Time-resolved luminescence and transient absorption spectroscopy studies confirmed that directed ET from RuP to NiP occurs efficiently in all systems on the nano- to microsecond time scale, through three distinct routes: reductive quenching of RuP in solution or on the surface of ZrO2 (“on particle” system) or oxidative quenching of RuP when the compounds were immobilized on TiO2 (“through particle” system). Our studies show that NiP can be used in a purely aqueous solution and on a semiconductor surface with a high degree of versatility. A high TOF of 460 ± 60 h–1 with a TON of 723 ± 171 for photocatalytic H2 generation with a molecular Ni catalyst in water and a photon-to-H2 quantum yield of approximately 10% were achieved for the homogeneous system.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: found
              Is Open Access

              Biochemistry

              (2003)
                Bookmark

                Author and article information

                Journal
                J Am Chem Soc
                J. Am. Chem. Soc
                ja
                jacsat
                Journal of the American Chemical Society
                American Chemical Society
                0002-7863
                1520-5126
                01 October 2013
                30 October 2013
                : 135
                : 43
                : 16168-16174
                Affiliations
                []Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States
                [§ ]School of Chemistry, University of East Anglia, Norwich Research Park , Norwich NR4 7TJ, United Kingdom
                []Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus , Didcot, Oxon OX11 0QX, United Kingdom
                [# ]Department of Biophysics, Medical School, University of Pecs , Szigeti ut 12, 7624 Pecs, Hungary
                Author notes
                Article
                10.1021/ja407265p
                3837517
                24083781
                ca9fa031-2802-43d8-a68d-ed9558c06bd7
                Copyright © 2013 American Chemical Society
                History
                : 18 July 2013
                Categories
                Article
                Custom metadata
                ja407265p
                ja-2013-07265p

                Chemistry
                Chemistry

                Comments

                Comment on this article