Interaction of phenols with old yellow enzyme. Physical evidence for charge-transfer complexes.

Abramovitz, Aaron S.; Massey, Vincent

doi:10.1016/s0021-9258(17)33165-4

Cited by 158 publications

(66 citation statements)

References 48 publications

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“…The long wavelength and breadth of the new absorbance are suggestive of a charge-transfer (CT) interaction, for example, with a nearby amino acid side chain or substrate analog ( 40 , 41 , 42 ). Since the band is not present in the WT, the introduced His-165 is a candidate participant.…”

Section: Resultsmentioning

confidence: 99%

Contrasting roles for two conserved arginines: Stabilizing flavin semiquinone or quaternary structure, in bifurcating electron transfer flavoproteins

Mohamed-Raseek

Miller

2022

Journal of Biological Chemistry

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Section: Resultsmentioning

confidence: 99%

Contrasting roles for two conserved arginines: Stabilizing flavin semiquinone or quaternary structure, in bifurcating electron transfer flavoproteins

Mohamed-Raseek

Miller

2022

Journal of Biological Chemistry

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“…[21] Moreover, a distinct peak at 394 nm appeared, which could be an indication of a lower amount of the anionic radical semiquinone species. [29][30][31][32] The high similarity of the absorbance spectrum of MmMmoC to that of the reductase from M. capsulatus (Bath) [33] suggests that these proteins have the same cofactor composition with one FAD and one [2Fe2S] cluster.…”

Section: Resultsmentioning

confidence: 99%

Catalytic and Spectroscopic Properties of the Halotolerant Soluble Methane Monooxygenase Reductase from Methylomonas methanica MC09

et al. 2022

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The soluble methane monooxygenase receives electrons from NADH via its reductase MmoC for oxidation of methane, which is itself an attractive C1 building block for a future bioeconomy. Herein, we present biochemical and spectroscopic insights into the reductase from the marine methanotroph Methylomonas methanica MC09. The presence of a flavin adenine dinucleotide (FAD) and [2Fe2S] cluster as its prosthetic group were revealed by reconstitution experiments, iron determination and electron paramagnetic resonance spectroscopy. As a true halotolerant enzyme, MmoC still showed 50 % of its specific activity at 2 M NaCl. We show that MmoC produces only trace amounts of superoxide, but mainly hydrogen peroxide during uncoupled turnover reactions. The characterization of a highly active reductase is an important step for future biotechnological applications of a halotolerant sMMO.

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“…The conjugation that is observed for lignin phenols (DBE ∼ 5), and even for the observed PAH-like compounds, is insufficient to absorb visible light; however, when relatively small lignin phenols are deprotonated in solution, they absorb light in the visible range due to the resonance stabilization of the phenolates -the red shift is much more pronounced for phenols with extra conjugation such as sinapaldehyde (Panossian et al, 2001). Our solution is not sufficiently basic (pH ∼ 5) for the deprotonated form to substantially exist in equilibrium (e.g., pKa for sinapaldehyde is 8.2, coniferaldehyde is 7.98, vanillin is 7.4, and bivanillin is 6.16; Ragnar et al, 2000); however, localized charge transfer interactions may facilitate the deprotonation of phenols at pH much lower than their pKa (Abramovitz and Massey, 1976). It is not clear why sinapaldehyde and coniferaldehyde do not correlate with MAC vis , but vanillylidene acetone with its additional sigma carbon does.…”

Section: Obsmentioning

confidence: 92%

Relationship between the molecular composition, visible light absorption, and health-related properties of smoldering woodsmoke aerosols

et al. 2020

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Abstract. Organic aerosols generated from the smoldering combustion of wood critically impact air quality and health for billions of people worldwide; yet, the links between the chemical components and the optical or biological effects of woodsmoke aerosol (WSA) are still poorly understood. In this work, an untargeted analysis of the molecular composition of smoldering WSA, generated in a controlled environment from nine types of heartwood fuels (African mahogany, birch, cherry, maple, pine, poplar, red oak, redwood, and walnut), identified several hundred compounds using gas chromatography mass spectrometry (GC-MS) and nano-electrospray high-resolution mass spectrometry (HRMS) with tandem multistage mass spectrometry (MSn). The effects of WSA on cell toxicity as well as gene expression dependent on the aryl hydrocarbon receptor (AhR) and estrogen receptor (ER) were characterized with cellular assays, and the visible mass absorption coefficients (MACvis) of WSA were measured with ultraviolet–visible spectroscopy. The WSAs studied in this work have significant levels of biological and toxicological activity, with exposure levels in both an outdoor and indoor environment similar to or greater than those of other toxicants. A correlation between the HRMS molecular composition and aerosol properties found that phenolic compounds from the oxidative decomposition of lignin are the main drivers of aerosol effects, while the cellulose decomposition products play a secondary role; e.g., levoglucosan is anticorrelated with multiple effects. Polycyclic aromatic hydrocarbons (PAHs) are not expected to form at the combustion temperature in this work, nor were they observed above the detection limit; thus, biological and optical properties of the smoldering WSA are not attributed to PAHs. Syringyl compounds tend to correlate with cell toxicity, while the more conjugated molecules (including several compounds assigned to dimers) have higher AhR activity and MACvis. The negative correlation between cell toxicity and AhR activity suggests that the toxicity of smoldering WSA to cells is not mediated by the AhR. Both mass-normalized biological outcomes have a statistically significant dependence on the degree of combustion of the wood. In addition, our observations support the fact that the visible light absorption of WSA is at least partially due to charge transfer effects in aerosols, as previously suggested. Finally, MACvis has no correlation with toxicity or receptor signaling, suggesting that key chromophores in this work are not biologically active on the endpoints tested.

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Interaction of phenols with old yellow enzyme. Physical evidence for charge-transfer complexes.

Cited by 158 publications

References 48 publications

Contrasting roles for two conserved arginines: Stabilizing flavin semiquinone or quaternary structure, in bifurcating electron transfer flavoproteins

Contrasting roles for two conserved arginines: Stabilizing flavin semiquinone or quaternary structure, in bifurcating electron transfer flavoproteins

Catalytic and Spectroscopic Properties of the Halotolerant Soluble Methane Monooxygenase Reductase from Methylomonas methanica MC09

Relationship between the molecular composition, visible light absorption, and health-related properties of smoldering woodsmoke aerosols

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