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Klaas J. Hellingwerf - One of the best experts on this subject based on the ideXlab platform.

  • confinement in crystal lattice alters entire photocycle pathway of the photoactive yellow protein
    Nature Communications, 2020
    Co-Authors: Patrick E Konold, Ivo H M Van Stokkum, Klaas J. Hellingwerf, Enis Arik, Jorn Weisenborn, Jos C Arents, John T M Kennis, Marie Louise Groot
    Abstract:

    Femtosecond time-resolved crystallography (TRC) on proteins enables resolving the spatial structure of short-lived photocycle intermediates. An open question is whether confinement and lower hydration of the proteins in the Crystalline State affect the light-induced structural transformations. Here, we measured the full photocycle dynamics of a signal transduction protein often used as model system in TRC, Photoactive Yellow Protein (PYP), in the Crystalline State and compared those to the dynamics in solution, utilizing electronic and vibrational transient absorption measurements from 100 fs over 12 decades in time. We find that the photocycle kinetics and structural dynamics of PYP in the Crystalline form deviate from those in solution from the very first steps following photon absorption. This illustrates that ultrafast TRC results cannot be uncritically extrapolated to in vivo function, and that comparative spectroscopic experiments on proteins in Crystalline and solution States can help identify structural intermediates under native conditions.

  • Photoactive Yellow Protein Studied by Ultraviolet-Visible Transient Absorption Spectroscopy
    2016
    Co-Authors: Author(s S. Yeremenko, Ivo H M Van Stokkum, Klaas J. Hellingwerf, K. Moffat, Sergey Yeremenko, Keith Y Moffat
    Abstract:

    Type article Title Influence of the Crystalline State on photoinduced dynamics of photoactive yellow protein studied by ultraviolet-visible transient absorption spectroscop

  • influence of the Crystalline State on photoinduced dynamics of photoactive yellow protein studied by ultraviolet visible transient absorption spectroscopy
    Biophysical Journal, 2006
    Co-Authors: Sergey Yeremenko, Ivo H M Van Stokkum, K. Moffat, Klaas J. Hellingwerf
    Abstract:

    Time-resolved ultraviolet-visible spectroscopy was used to characterize the photocycle transitions in single crystals of wild-type and the E-46Q mutant of photoactive yellow protein (PYP) with microsecond time resolution. The results were compared with the results of similar measurements on aqueous solutions of these two variants of PYP, with and without the components present in the mother liquor of crystals. The experimental data were analyzed with global and target analysis. Distinct differences in the reaction path of a PYP molecule are observed between these conditions when it progresses through its photocycle. In the Crystalline State i), much faster relaxation of the late blue-shifted photocycle intermediate back to the ground State is observed; ii), this intermediate in Crystalline PYP absorbs at 380 nm, rather than at 350-360 nm in solution; and iii), for various intermediates of this photocycle the forward reaction through the photocycle directly competes with a branching reaction that leads directly to the ground State. Significantly, with these altered characteristics, the spectroscopic data on PYP are fully consistent with the structural data obtained for this photoreceptor protein with time-resolved x-ray diffraction analysis, particularly for wild-type PYP.

Wei Huang - One of the best experts on this subject based on the ideXlab platform.

  • stimuli responsive solid State emission from o carborane tetraphenylethene dyads induced by twisted intramolecular charge transfer in the Crystalline State
    Journal of Materials Chemistry C, 2018
    Co-Authors: Junfeng Li, Chenglong Yang, Xuelei Peng, Ying Chen, Qi Qi, Wei Huang
    Abstract:

    We described herein a unique dual emission switching process from o-carborane–tetraphenylethene (TPE) dyads induced by twisted intramolecular charge transfer (TICT) in the Crystalline State. Two novel o-carborane–tetraphenylethylene dyads, composed of a TPE core bearing o-carborane units, were designed, synthesized and characterized. Crystalline o-1 and o-2 were obtained with mono-substituted and bi-substituted o-carborane units, respectively. Both dyads presented locally excited (LE) emission and TICT induced emission in solutions. Crystalline o-1 demonstrated aggregation-induced emission (AIE), crystallization-induced emission (CIE), thermochromism, vapochromism, and mechanical luminescence (MCL) properties via TICT, while Crystalline o-2 showed only the AIE and CIE properties orginating from the inherent ICT States. From the mechanistic investigations and theoretical calculations, it was demonstrated that the emission was reversible and switchable between green and orange colors for o-1, which was assigned to the facile TICT modulation in the solid State. The results manifest that the unique three-dimensional o-carborane cluster's structure plays an important role in precisely controlling the molecular packing patterns and conformations to achieve TICT emission.

Ivo H M Van Stokkum - One of the best experts on this subject based on the ideXlab platform.

  • confinement in crystal lattice alters entire photocycle pathway of the photoactive yellow protein
    Nature Communications, 2020
    Co-Authors: Patrick E Konold, Ivo H M Van Stokkum, Klaas J. Hellingwerf, Enis Arik, Jorn Weisenborn, Jos C Arents, John T M Kennis, Marie Louise Groot
    Abstract:

    Femtosecond time-resolved crystallography (TRC) on proteins enables resolving the spatial structure of short-lived photocycle intermediates. An open question is whether confinement and lower hydration of the proteins in the Crystalline State affect the light-induced structural transformations. Here, we measured the full photocycle dynamics of a signal transduction protein often used as model system in TRC, Photoactive Yellow Protein (PYP), in the Crystalline State and compared those to the dynamics in solution, utilizing electronic and vibrational transient absorption measurements from 100 fs over 12 decades in time. We find that the photocycle kinetics and structural dynamics of PYP in the Crystalline form deviate from those in solution from the very first steps following photon absorption. This illustrates that ultrafast TRC results cannot be uncritically extrapolated to in vivo function, and that comparative spectroscopic experiments on proteins in Crystalline and solution States can help identify structural intermediates under native conditions.

  • Photoactive Yellow Protein Studied by Ultraviolet-Visible Transient Absorption Spectroscopy
    2016
    Co-Authors: Author(s S. Yeremenko, Ivo H M Van Stokkum, Klaas J. Hellingwerf, K. Moffat, Sergey Yeremenko, Keith Y Moffat
    Abstract:

    Type article Title Influence of the Crystalline State on photoinduced dynamics of photoactive yellow protein studied by ultraviolet-visible transient absorption spectroscop

  • influence of the Crystalline State on photoinduced dynamics of photoactive yellow protein studied by ultraviolet visible transient absorption spectroscopy
    Biophysical Journal, 2006
    Co-Authors: Sergey Yeremenko, Ivo H M Van Stokkum, K. Moffat, Klaas J. Hellingwerf
    Abstract:

    Time-resolved ultraviolet-visible spectroscopy was used to characterize the photocycle transitions in single crystals of wild-type and the E-46Q mutant of photoactive yellow protein (PYP) with microsecond time resolution. The results were compared with the results of similar measurements on aqueous solutions of these two variants of PYP, with and without the components present in the mother liquor of crystals. The experimental data were analyzed with global and target analysis. Distinct differences in the reaction path of a PYP molecule are observed between these conditions when it progresses through its photocycle. In the Crystalline State i), much faster relaxation of the late blue-shifted photocycle intermediate back to the ground State is observed; ii), this intermediate in Crystalline PYP absorbs at 380 nm, rather than at 350-360 nm in solution; and iii), for various intermediates of this photocycle the forward reaction through the photocycle directly competes with a branching reaction that leads directly to the ground State. Significantly, with these altered characteristics, the spectroscopic data on PYP are fully consistent with the structural data obtained for this photoreceptor protein with time-resolved x-ray diffraction analysis, particularly for wild-type PYP.

Katarzyna ślepokura - One of the best experts on this subject based on the ideXlab platform.

  • dihydroxyacetone phosphate dhap in the Crystalline State monomeric and dimeric forms
    Carbohydrate Research, 2010
    Co-Authors: Katarzyna ślepokura
    Abstract:

    Abstract It was shown that dihydroxyacetone phosphate may exist in both monomeric DHAP (C3H7O6P) and dimeric DHAP-dimer (C6H14O12P2) form. Monomeric DHAP was obtained in the form of four Crystalline salts: CaCl(DHAP)·2.9H2O (7a), Ca2Cl3(DHAP)·5H2O (7b), CaCl(DHAP)·2H2O (7c), and CaBr(DHAP)·5H2O (7d) by crystallization from aqueous solutions containing DHAP acid and CaCl2 or CaBr2, or by direct crystallization from a solution containing DHAP precursor and CaCl2. At least one of the salts is stable and may be stored in the Crystalline State at room temperature for several months. The dimeric form was obtained by slow saturation of free DHAP syrup with ammonia at −18 °C and isolated in the form of its hydrated diammonium salt (NH4)2(DHAP-dimer)·4H2O (8). The synthesis of the compounds, their crystallization, and crystal structures determined by X-ray crystallography are described. In all 7a–d monomeric DHAP exists in the monoanionic form in an extended (in-plane) cisoid conformation, with both hydroxyl and ester oxygen atoms being synperiplanar to the carbonyl O atom. The crucial structural feature is the coordination manner, in which the terminal phosphate oxygen atoms act as chelating as well as bridging atoms for the calcium cations. Additionally, the DHAP monoanions chelate another Ca2+ by the α-hydroxycarbonyl moiety, in a manner observed previously in dihydroxyacetone (DHA) calcium chloride complexes. In dimeric 8 the anion is a trans isomer with the dioxane ring in a chair conformation with the hydroxyl groups in axial positions and the phosphomethyl group in an equatorial position.

  • structure of cyclic dihydroxyacetone phosphate dimethyl acetal a cyclic dhap precursor in the Crystalline State
    Carbohydrate Research, 2008
    Co-Authors: Katarzyna ślepokura
    Abstract:

    Abstract The six-membered cyclic phosphate diester, 5,5-dimethoxy-2-oxo-1,3,2-dioxaphosphorinane-2-ol, the dimethyl acetal of cyclic dihydroxyacetone phosphate, (MeO)2cDHAP, was obtained by the isolation of an intermediate in the basic hydrolysis of the cyclic triester derivative. The compound had been isolated in the form of the Crystalline cyclohexylammonium (cha) salts: (cha)[(MeO)2cDHAP]·3H2O (5a) and (cha)[(MeO)2cDHAP]·H2O (5b), which were then converted into the free acid: (H5O2)[(MeO)2cDHAP] (5c) and then into a series of different salts: Na[(MeO)2cDHAP]·2H2O (5d), K[(MeO)2cDHAP]·1.5H2O (5e), K[(MeO)2cDHAP]·0.5H2O (5e′), Ca[(MeO)2cDHAP]2·2H2O (5f), CaK[(MeO)2cDHAP]3·2H2O (5g) and NH4[(MeO)2cDHAP] (5h). The synthesis of the compounds, their crystallization and crystal structures determined by X-ray crystallography are described. The most interesting structural feature observed in 5a–g anions in the Crystalline State is the chair conformation of the P/O/C/C/C/O 1,3,2-dioxaphosphorinane ring, which is generally not flattened, in contrast to the deformations often observed in the analogous aryl derivatives (also in (MeO)2cDHAP(Ph); Ślepokura, K.; Lis, T. Acta Crystallogr. Sect. C2004, 60, o315–o317). However, the anion in crystal 5h is disordered and exists in two conformations, 76% of which is the skew, S, conformation, not observed so far in the compounds of related structure.

Arbuzov B. - One of the best experts on this subject based on the ideXlab platform.