Time-resolved photothermal methods: accessing time-resolved thermodynamics of photoinduced processes in chemistry and biology

Gensch, Thomas; Viappiani, Cristiano

doi:10.1039/b303177b

Cited by 79 publications

(30 citation statements)

References 228 publications

(245 reference statements)

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“…The first striking feature is that the amplitude of the wave detected for Tf -trHb-CO is larger than that observed for the reference compound. This is consistent with an exothermic reaction and/or with the presence of a concomitant structural volume change [33], [34]. Moreover, the waveform of Tf -trHb-CO is delayed in comparison with that of the calorimetric reference, the delay becoming especially appreciable at low temperatures.…”

Section: Resultssupporting

confidence: 76%

Following Ligand Migration Pathways from Picoseconds to Milliseconds in Type II Truncated Hemoglobin from Thermobifida fusca

Marcelli¹,

Abbruzzetti

Bustamante

et al. 2012

PLoS ONE

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CO recombination kinetics has been investigated in the type II truncated hemoglobin from Thermobifida fusca (Tf-trHb) over more than 10 time decades (from 1 ps to ∼100 ms) by combining femtosecond transient absorption, nanosecond laser flash photolysis and optoacoustic spectroscopy. Photolysis is followed by a rapid geminate recombination with a time constant of ∼2 ns representing almost 60% of the overall reaction. An additional, small amplitude geminate recombination was identified at ∼100 ns. Finally, CO pressure dependent measurements brought out the presence of two transient species in the second order rebinding phase, with time constants ranging from ∼3 to ∼100 ms. The available experimental evidence suggests that the two transients are due to the presence of two conformations which do not interconvert within the time frame of the experiment. Computational studies revealed that the plasticity of protein structure is able to define a branched pathway connecting the ligand binding site and the solvent. This allowed to build a kinetic model capable of describing the complete time course of the CO rebinding kinetics to Tf-trHb.

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Section: Resultssupporting

confidence: 76%

Following Ligand Migration Pathways from Picoseconds to Milliseconds in Type II Truncated Hemoglobin from Thermobifida fusca

Marcelli¹,

Abbruzzetti

Bustamante

et al. 2012

PLoS ONE

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“…These may be attributed, e.g., to structural changes of the protein, protolytic reactions, water binding, oxygen release, or even ionic rearrangements in the solvent environment (Braslavsky 1986;Braslavsky and Heibel 1992;Gensch and Viappiani 2003). In the P 680 * ?…”

Section: Discussionmentioning

confidence: 97%

“…The determination of reaction enthalpies is highly desirable, but especially challenging. Photoacoustic (PA) or photothermal methods in principle allow for the direct determination of reaction enthalpies in photoenzymes (Braslavsky and Heibel 1992;Gensch and Viappiani 2003).…”

Section: Introductionmentioning

confidence: 99%

Energetics and kinetics of photosynthetic water oxidation studied by photothermal beam deflection (PBD) experiments

et al. 2009

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Determination of thermodynamic parameters of water oxidation at the photosystem II (PSII) manganese complex is a major challenge. Photothermal beam deflection (PBD) spectroscopy determines enthalpy changes (ΔH) and apparent volume changes which are coupled with electron transfer in the S-state cycle (Krivanek R, Dau H, Haumann M (2008) Biophys J 94: 1890–1903). Recent PBD results on formation of the Q⁻(A)/Y(•+)(Z) radical pair suggest a value of ΔH similar to the free energy change, ΔG, of -540±40 meV previously determined by the analysis of recombination fluorescence, but presently the uncertainty range of ΔH values determined by PBD is still high (±250 meV). In the oxygen-evolving transition, S₃−−>S₀, the enthalpy change may be close to zero. A prominent non-thermal signal is associated with both Q⁻(A)/Y(•+)(Z) formation (<1 μs) and the S₃−−>S₀ transition (~1 ms). The observed (apparent) volume expansion (ΔV of about +40 Å³ per PSII unit) in the S₃−−>S₀ transition seems to revert, at least partially, the contractions on lower S-transitions and may also comprise contributions from O₂ and proton release. The observed volume changes show that the S₃−−>S₀ transition is accompanied by significant nuclear movements, which likely are of importance with respect to energetics and mechanism of photosynthetic water oxidation. Detailed PBD studies on all S-transitions will contribute to the progress in PSII research by providing insights not accessible by other spectroscopic methods.

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“…The physical principle behind photothermal methods is that a photo-excited molecule dissipates excess energy via vibrational relaxation to the ground state, resulting in thermal heating of the surrounding solvent 1,12 . For solvents such as water, this produces a rapid volume expansion (ΔV th ).…”

Section: Discussionmentioning

confidence: 99%

“…Photo-thermal methods such as photoacoustic calorimetry, photothermal beam deflection (PDB), and transient grating coupled with nanosecond laser excitation represent a powerful alternative to transient optical spectroscopies for time-resolved studies of short-lived intermediates 1,2 . In contrast to optical techniques, such as transient absorption and IR spectroscopy, that monitor the time profile of absorption changes in the chromophore surrounding; photothermal techniques detect the time-dependence of heat/volume changes and therefore are valuable tools for investigating time profiles of optically "silent" processes.…”

Section: Introductionmentioning

confidence: 99%

Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection

González

Mikšovská

2014

JoVE

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Photothermal beam deflection together with photo-acoustic calorimetry and thermal grating belongs to the family of photothermal methods that monitor the time-profile volume and enthalpy changes of light induced conformational changes in proteins on microsecond to millisecond timescales that are not accessible using traditional stop-flow instruments. In addition, since overall changes in volume and/or enthalpy are probed, these techniques can be applied to proteins and other biomacromolecules that lack a fluorophore and or a chromophore label. To monitor dynamics and energetics of structural changes associated with Ca 2+ binding to calcium transducers, such neuronal calcium sensors, a caged calcium compound, DM-nitrophen, is employed to photo-trigger a fast (τ < 20 μsec) increase in free calcium concentration and the associated volume and enthalpy changes are probed using photothermal beam deflection technique. Video LinkThe video component of this article can be found at

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Time-resolved photothermal methods: accessing time-resolved thermodynamics of photoinduced processes in chemistry and biology

Cited by 79 publications

References 228 publications

Following Ligand Migration Pathways from Picoseconds to Milliseconds in Type II Truncated Hemoglobin from Thermobifida fusca

Following Ligand Migration Pathways from Picoseconds to Milliseconds in Type II Truncated Hemoglobin from Thermobifida fusca

Energetics and kinetics of photosynthetic water oxidation studied by photothermal beam deflection (PBD) experiments

Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection

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