0000000000812929

AUTHOR

Vaibhav Modi

showing 5 related works from this author

Protonation of the Biliverdin IXα Chromophore in the Red and Far-Red Photoactive States of a Bacteriophytochrome

2019

The tetrapyrrole chromophore biliverdin IXα (BV) in the bacteriophytochrome from Deinococcus radiodurans (DrBphP) is usually assumed to be fully protonated, but this assumption has not been systematically validated by experiments or extensive computations. Here, we use force field molecular dynamics simulations and quantum mechanics/molecular mechanics calculations with density functional theory and XMCQDPT2 methods to investigate the effect of the five most probable protonation forms of BV on structural stability, binding pocket interactions, and absorption spectra in the two photochromic states of DrBphP. While agreement with X-ray structural data and measured UV/vis spectra suggest that …

Absorption spectroscopyProtein ConformationPopulationProtonationMolecular Dynamics SimulationCrystallography X-Ray010402 general chemistryPhotochemistry01 natural sciencesArticlequantum chemistrychemistry.chemical_compoundMolecular dynamicsPhotochromismBacterial Proteins0103 physical scienceskvanttikemiaMaterials ChemistrymolekyylidynamiikkaPhysical and Theoretical Chemistryeducationta116excited statesphytochromeeducation.field_of_studyBinding SitesBiliverdin010304 chemical physicsChemistryBiliverdineta1182Chromophoremolecular dynamics3. Good health0104 chemical sciencesSurfaces Coatings and FilmsSpectrophotometry UltravioletDensity functional theoryDeinococcusvalokemiaproteiinitThe Journal of Physical Chemistry B
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The Photocycle of Bacteriophytochrome Is Initiated by Counterclockwise Chromophore Isomerization.

2022

Photoactivation of bacteriophytochrome involves a cis–trans photoisomerization of a biliverdin chromophore, but neither the precise sequence of events nor the direction of the isomerization is known. Here, we used nonadiabatic molecular dynamics simulations on the photosensory protein dimer to resolve the isomerization mechanism in atomic detail. In our simulations the photoisomerization of the D ring occurs in the counterclockwise direction. On a subpicosecond time scale, the photoexcited chromophore adopts a short-lived intermediate with a highly twisted configuration stabilized by an extended hydrogen-bonding network. Within tens of picoseconds, these hydrogen bonds break, allowing the c…

isomeriaBiliverdinephotoisomerizationHydrogen BondingMolecular Dynamics Simulationlaskennallinen kemiacomputational chemistryisomerizationBacterial ProteinsIsomerismchromophoresGeneral Materials SciencevalokemiaproteiinitPhysical and Theoretical ChemistryabsorptionThe journal of physical chemistry letters
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Chromophore-Protein Interplay During the Phytochrome Photocycle Revealed by Step-Scan FTIR Spectroscopy

2018

Phytochrome proteins regulate many photoresponses of plants and microorganisms. Light absorption causes isomerization of the biliverdin chromophore, which triggers a series of structural changes to activate the signaling domains of the protein. However, the structural changes are elusive, and therefore the molecular mechanism of signal transduction remains poorly understood. Here, we apply two-color step-scan infrared spectroscopy to the bacteriophytochrome from Deinococcus radiodurans. We show by recordings in H2O and D2O that the hydrogen bonds to the biliverdin D-ring carbonyl become disordered in the first intermediate (Lumi-R) forming a dynamic microenvironment, then completely detach …

0301 basic medicineInfrared spectroscopyMolecular Dynamics SimulationBiochemistryCatalysis03 medical and health scienceschemistry.chemical_compoundchromophore-protein interplayColloid and Surface ChemistryBacterial ProteinsSpectroscopy Fourier Transform InfraredPeptide bondta116BiliverdinbiologyPhytochromeHydrogen bondBiliverdineta1182WaterHydrogen BondingDeinococcus radioduransGeneral ChemistryChromophorePhotochemical Processesbiology.organism_classification030104 developmental biologychemistryBiophysicsProtein Conformation beta-StrandDeinococcusPhytochromevalokemiaproteiinitSignal transductionstep-scan FTIR spectroscopyAdenylyl CyclasesJournal of the American Chemical Society
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Observe while it happens : catching photoactive proteins in the act with non-adiabatic molecular dynamics simulations

2020

Organisms use photo-receptors to react to light. The first step is usually the absorption of a photon by a prosthetic group embedded inside the photo-receptor, often a conjugated chromophore. The electronic changes in the chromophore induced by photo-absorption can trigger a cascade of structural or chemical transformations that culminate into a response to light. Understanding how these proteins have evolved to mediate their activation process has remained challenging because the required time and spacial resolutions are notoriously difficult to achieve experimentally. Therefore, mechanistic insights into photoreceptor activation have been predominantly obtained with computer simulations. …

photoactive proteinsmolecular biologysense organsproteiinitmolekyylibiologia
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Protonation of the Biliverdin IXα Chromophore in the Red and Far-Red Photoactive States of Bacteriophytochrome

2019

The tetrapyrrole chromophore biliverdin IXα (BV) in the bacteriophytochrome from Deinococcus radiodurans (DrBphP) is usually assumed to be fully protonated, but this assumption has not been systematically validated by experiments or extensive computations. Here, we use force field molecular dynamics simulations and quantum mechanics/molecular mechanics calculations with density functional theory and XMCQDPT2 methods to investigate the effect of the five most probable protonation forms of BV on structural stability, binding pocket interactions, and absorption spectra in the two photochromic states of DrBphP. While agreement with X-ray structural data and measured UV/vis spectra suggest that …

phytochromekvanttikemiamolekyylidynamiikkavalokemiaproteiinitexcited states
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