The Experts below are selected from a list of 1155 Experts worldwide ranked by ideXlab platform
Klaas J Hellingwerf - One of the best experts on this subject based on the ideXlab platform.
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resonance raman evidence that the thioester linked 4 hydroxycinnamyl chromophore of photoactive yellow protein is deprotonated
Biochemistry, 1995Co-Authors: Munsok Kim, Richard A Mathies, Wouter D Hoff, Klaas J HellingwerfAbstract:Resonance Raman spectra of the ground state of photoactive yellow protein (PYP), a photoactive pigment found in Ectothiorhodospira halophila, have been obtained with excitation at 413.1 nm using a microspinning sample cell. The resonance Raman spectra of the thioester-linked 4-hydroxycinnamyl chromophore in the protein are compared with the preresonance Raman spectra of the 4-hydroxycinnamyl phenyl thioester and 4-hydroxycinnamic acid model compounds at various pH values. Bands at 1568, 1542, 1500, 1434, and 1166 cm-' in the Raman spectrum of the Anionic form of the 4-hydroxycinnamyl phenyl thioester are shown to be characteristic for the deprotonation of the chromophore. The observation of bands in PYP exhibiting very similar frequency and intensity patterns provides strong evidence that the chromophore in PYP is stabilized as a Phenolate Anion at pH 7.4, in support of conclusions from crystallographic studies. Furthermore, the insensitivity of the PYP Raman spectrum to placement of the protein in D20 buffer is consistent with the absence of the exchangeable phenolic proton on the cinnamyl chromophore. These results establish the feasibility of elucidating the molecular mechanism of light-to- information transduction by this new photosensory pigment with resonance Raman spectroscopy.
Elizabeth D Getzoff - One of the best experts on this subject based on the ideXlab platform.
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complete chemical structure of photoactive yellow protein novel thioester linked 4 hydroxycinnamyl chromophore and photocycle chemistry
Biochemistry, 1994Co-Authors: Manuel Baca, Gloria E O Borgstahl, Maurice Boissinot, Patrick M Burke, Dewight Williams, Kelly Slater, Elizabeth D GetzoffAbstract:The unique ability of photoactive proteins to capture and use energy from a photon of light depends on the chromophore, its linkage to the protein, and the surrounding protein environment. To understand the molecular mechanisms by which a chromophore and protein interact to undergo a light cycle, we are studying photoactive yellow protein (PYP), a 14-kDa water-soluble photoreceptor from Ectothiorhodospira halophila with a photocycle similar to that of sensory rhodopsin. Here, we report the cloning and sequencing of the pyp gene and the chemical identification of both the chromophore and its covalent linkage to the protein. Elemental composition data from high-resolution mass spectrometry of a proteolytically derived chromopeptide, pH titrations and UV-visible spectroscopy of the protein-bound and chemically released chromophore, and fragmentation mass spectrometry of the liberated chromophore amide were combined with results from the 1.4-A-resolution protein crystal structure to identify the chromophore in PYP as a 4-hydroxycinnamyl group covalently bound to the sole cysteine residue via a thioester linkage. While 4-hydroxycinnamate is a metabolic product of the phenylpropanoid pathway and a key molecule in plant stress response, this is the first report of covalent modification of a protein by this group. In the dark (yellow) state of PYP, the protein stabilizes the chromophore as the deprotonated Phenolate Anion. By combining our biochemical characterization of the chromophore with other published observations, we propose a chemical basis for the photocycle: following the initial absorption of a photon, the photocycle of PYP involves protonation of the chromophore to a neutral phenol form corresponding to the observed photobleached intermediate.
Zdenek Havlas - One of the best experts on this subject based on the ideXlab platform.
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interactions in molecular crystals 118 the sodium benzo 15 crown 5 salt of 2 6 di tert butyl 4 methylphenol a sodium Phenolate with an extremely short na o distance structure and density functional calculations
Chemische Berichte, 1997Co-Authors: Hans Bock, Rudiger Dienelt, Christian Nather, Zdenek HavlasAbstract:The structure of crystals, isolated in low yield, from the attempted metallation of diphenylmethane in tetrahydrofuran solution containing benzo-15-crown-5 at a sodium metal mirror is determined, surprisingly, to be the sodium (benzo-15-crown) salt of 2,6-di(tert-butyl)-4-methylphenol, an antioxidative stabilizer to prevent ether peroxide formation. The structure of the solvent-shared contact ion pair (monoclinic P21/n, Z = 4, R1 = 0.06) proves a strong Na+…O− interaction at the extremely short distance of only 216 pm, a sixfold O-coordination of the Na+ cation in a pentagonal pyramid, and a hemispherical distortion of the crown ether. Density functional calculations at the B3LYP/6-31G* level, based on the structural data, reproduce, within a one-dimensional hypersurface approach, the rather short Na+…O− distance, and predict Mulliken charges of +0.32 for Na′ and -0.71 for 0−, as well as a considerable polarization of the trialkyl Phenolate Anion.
Munsok Kim - One of the best experts on this subject based on the ideXlab platform.
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resonance raman evidence that the thioester linked 4 hydroxycinnamyl chromophore of photoactive yellow protein is deprotonated
Biochemistry, 1995Co-Authors: Munsok Kim, Richard A Mathies, Wouter D Hoff, Klaas J HellingwerfAbstract:Resonance Raman spectra of the ground state of photoactive yellow protein (PYP), a photoactive pigment found in Ectothiorhodospira halophila, have been obtained with excitation at 413.1 nm using a microspinning sample cell. The resonance Raman spectra of the thioester-linked 4-hydroxycinnamyl chromophore in the protein are compared with the preresonance Raman spectra of the 4-hydroxycinnamyl phenyl thioester and 4-hydroxycinnamic acid model compounds at various pH values. Bands at 1568, 1542, 1500, 1434, and 1166 cm-' in the Raman spectrum of the Anionic form of the 4-hydroxycinnamyl phenyl thioester are shown to be characteristic for the deprotonation of the chromophore. The observation of bands in PYP exhibiting very similar frequency and intensity patterns provides strong evidence that the chromophore in PYP is stabilized as a Phenolate Anion at pH 7.4, in support of conclusions from crystallographic studies. Furthermore, the insensitivity of the PYP Raman spectrum to placement of the protein in D20 buffer is consistent with the absence of the exchangeable phenolic proton on the cinnamyl chromophore. These results establish the feasibility of elucidating the molecular mechanism of light-to- information transduction by this new photosensory pigment with resonance Raman spectroscopy.
Manuel Baca - One of the best experts on this subject based on the ideXlab platform.
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complete chemical structure of photoactive yellow protein novel thioester linked 4 hydroxycinnamyl chromophore and photocycle chemistry
Biochemistry, 1994Co-Authors: Manuel Baca, Gloria E O Borgstahl, Maurice Boissinot, Patrick M Burke, Dewight Williams, Kelly Slater, Elizabeth D GetzoffAbstract:The unique ability of photoactive proteins to capture and use energy from a photon of light depends on the chromophore, its linkage to the protein, and the surrounding protein environment. To understand the molecular mechanisms by which a chromophore and protein interact to undergo a light cycle, we are studying photoactive yellow protein (PYP), a 14-kDa water-soluble photoreceptor from Ectothiorhodospira halophila with a photocycle similar to that of sensory rhodopsin. Here, we report the cloning and sequencing of the pyp gene and the chemical identification of both the chromophore and its covalent linkage to the protein. Elemental composition data from high-resolution mass spectrometry of a proteolytically derived chromopeptide, pH titrations and UV-visible spectroscopy of the protein-bound and chemically released chromophore, and fragmentation mass spectrometry of the liberated chromophore amide were combined with results from the 1.4-A-resolution protein crystal structure to identify the chromophore in PYP as a 4-hydroxycinnamyl group covalently bound to the sole cysteine residue via a thioester linkage. While 4-hydroxycinnamate is a metabolic product of the phenylpropanoid pathway and a key molecule in plant stress response, this is the first report of covalent modification of a protein by this group. In the dark (yellow) state of PYP, the protein stabilizes the chromophore as the deprotonated Phenolate Anion. By combining our biochemical characterization of the chromophore with other published observations, we propose a chemical basis for the photocycle: following the initial absorption of a photon, the photocycle of PYP involves protonation of the chromophore to a neutral phenol form corresponding to the observed photobleached intermediate.