Redox State Dependence of Axial Ligand Dynamics in <i>Nitrosomonas europaea</i> Cytochrome <i>c</i>₅₅₂

Analysis of NMR spectra reveals that the heme axial Met ligand orientation and dynamics in <i>Nitrosomonas europaea</i> cytochrome <i>c</i>₅₅₂ (<i>Ne</i> cyt <i>c</i>) are dependent on the heme redox state. In the oxidized state, the heme axial Met is fluxional, interconverting between two conformers related to each other by inversion through the Met δS atom. In the reduced state, there is no evidence of fluxionality, with the Met occupying one conformation similar to that seen in the homologous <i>Pseudomonas aeruginosa</i> cytochrome <i>c</i>₅₅₁. Comparison of the observed and calculated pseudocontact shifts for oxidized <i>Ne</i> cyt <i>c</i> using the reduced protein structure as a reference structure reveals a redox-dependent change in the structure of the loop bearing the axial Met (loop 3). Analysis of nuclear Overhauser effects (NOEs) and existing structural data provides further support for the redox state dependence of the loop 3 structure. Implications for electron transfer function are discussed

Data_Sheet_1_COVID-19 Pandemic Impact on Respiratory Infectious Diseases in Primary Care Practice in Children.docx

Background: The coronavirus disease 2019 (COVID-19) pandemic led to day care and school closures and children staying home for several months. When they gradually returned, aggressive regulations were implemented in New York State to reduce viral transmission.Method: An ongoing prospective study occurring in the Rochester, NY region, focused on early childhood respiratory infectious diseases, afforded an opportunity to assess the impact of the pandemic on the incidence of these illnesses in a primary care outpatient setting. Physician-diagnosed, medically attended infection visits were assessed in two child cohorts, age 6–36 months old: from March 15 to December 31, 2020 (the pandemic period) compared to the same months in 2019 (prepandemic). Nasopharyngeal colonization by potential otopathogens during healthy/well-child and acute otitis media (AOM) visits was evaluated.Results: One hundred and forty-four children were included in the pandemic cohort and 215 in the prepandemic cohort. The pandemic cohort of children experienced 1.8-fold less frequent infectious disease visits during the pandemic (p Conclusion: In primary care pediatric practice, during the first 9 months of the COVID-19 pandemic, significant decreases in the frequency of multiple respiratory infections and nasopharyngeal colonization by potential bacterial respiratory pathogens occurred in children age 6–36 months old.</p

Benzothiophene-Based Cross-Conjugated Organic Dyes for High-Photocurrent Dye-Sensitized Solar Cells with Photocurrents up to 27 mA/cm²

Dye-sensitized solar cells (DSCs) are a third-generation solar cell technology that performs well in many environments such as low light intensity situations. High-photocurrent DSCs are important for tandem photovoltaic applications, where light intensity is divided between light absorbing layers. Dyes that absorb near-infrared (NIR) photons with appropriately positioned highest occupied molecular orbital (HOMO) energy levels are needed for high-photocurrent DSC devices. In this work, a cross-conjugated double-donor–π bridge–acceptor (ccDD–π–A) type dye architecture is studied with four cross-conjugated benzo[b]thiophene-based dyes (ND4, ND5, ND6, and ND7). The dyes were studied via density functional theory and time-dependent density functional theory calculations to probe the orbital overlap and intramolecular charge transfer character of the dyes. Absorption spectroscopy was carried out to evaluate the extinction coefficient and absorption profiles of the dyes in solution and on TiO2 films. The energetics of the dyes were characterized by using cyclic voltammetry experiments in conjunction with optical spectroscopy. DSC devices fabricated with the dyes were characterized through current density–voltage curves and incident photon-to-current conversion efficiency measurements. ND7-based devices produced a maximum photocurrent of 27 mA/cm2 with an incident photon-to-current conversion efficiency onset of ∼1000 nm

Folding, Conformational Changes, and Dynamics of Cytochromes <i>c</i> Probed by NMR Spectroscopy

NMR spectroscopy has become a vital tool for studies of protein conformational changes and dynamics. Oxidized Fe(III)cytochromes c are a particularly attractive target for NMR analysis because their paramagnetism (S = 1/2) leads to high 1H chemical shift dispersion, even for unfolded or otherwise disordered states. In addition, analysis of shifts induced by the hyperfine interaction reveals details of the structure of the heme and its ligands for native and nonnative protein conformational states. The use of NMR spectroscopy to investigate the folding and dynamics of paramagnetic cytochromes c is reviewed here. Studies of nonnative conformations formed by denaturation and by anomalous in vivo maturation (heme attachment) are facilitated by the paramagnetic, low-spin nature of native and nonnative forms of cytochromes c. Investigation of the dynamics of folded cytochromes c also are aided by their paramagnetism. As an example of this analysis, the expression in Escherichia coli of cytochrome c552 from Nitrosomonas europaea is reported here, along with analysis of its unusual heme hyperfine shifts. The results are suggestive of heme axial methionine fluxion in N. europaea ferricytochrome c552. The application of NMR spectroscopy to investigate paramagnetic cytochrome c folding and dynamics has advanced our understanding of the structure and dynamics of both native and nonnative states of heme proteins

Nickel-Based Two-Electron Redox Shuttle for Dye-Sensitized Solar Cells in Low Light Applications

Dye-sensitized solar cells (DSCs) are important to indoor solar powered devices and energy sustainable buildings because of their remarkable performance under indoor/ambient light conditions. Triiodide/iodide (I3–/I–) has been used as the most common redox mediator in DSCs because of its desirable kinetic properties and multielectron redox cycle. However, the low redox potential, corrosiveness, competitive visible light absorption, and lack of tunability of this redox mediator limit its performance in many DSC devices. Here we report a class of transition metal complex redox shuttles which operate on a similar multielectron redox cycle as I3–/I– while maintaining desirable kinetics and improving on its limitations. These complexes, nickel dithiocarbamates, were evaluated as redox shuttles in DSCs, which exhibited excellent performance under low light conditions. The recombination behavior of the redox shuttles with electrons in TiO2, dye regeneration behavior, and counter electrode electron transfer resistance were studied via chronoamperometry and electrochemical impedance spectroscopy (EIS). Further, DSC devices were studied with the Ni-based redox shuttles via incident photon-to-current conversion efficiencies (IPCEs) and current–voltage (J–V) curves under varied light intensities. The Ni-based redox shuttles showed up to 20.4% power conversion efficiency under fluorescent illumination, which was higher than I3–/I–-based devices (13%) at similar electrolyte concentrations. Taken together, these results show that nickel dithiocarbamate redox shuttles have faster rates of dye regeneration than the I3–/I– shuttle but suffer from faster recombination of photoinjected electrons with oxidized Ni­(IV) species, which decrease photovoltages

sj-jpeg-2-jcn-10.1177_08830738231169411 - Supplemental material for Neuroimaging Findings in Vitamin B₁₂-Deficient Infants With Neurologic Features

Supplemental material, sj-jpeg-2-jcn-10.1177_08830738231169411 for Neuroimaging Findings in Vitamin B12-Deficient Infants With Neurologic Features by Anjali Yadav, Chandrika Azad, Ravinder Kaur, Vishal Guglani, Seema Gupta and Sukanya Mitra in Journal of Child Neurology</p

sj-png-3-jcn-10.1177_08830738231169411 - Supplemental material for Neuroimaging Findings in Vitamin B₁₂-Deficient Infants With Neurologic Features

Supplemental material, sj-png-3-jcn-10.1177_08830738231169411 for Neuroimaging Findings in Vitamin B12-Deficient Infants With Neurologic Features by Anjali Yadav, Chandrika Azad, Ravinder Kaur, Vishal Guglani, Seema Gupta and Sukanya Mitra in Journal of Child Neurology</p

sj-docx-1-jcn-10.1177_08830738231169411 - Supplemental material for Neuroimaging Findings in Vitamin B₁₂-Deficient Infants With Neurologic Features

Supplemental material, sj-docx-1-jcn-10.1177_08830738231169411 for Neuroimaging Findings in Vitamin B12-Deficient Infants With Neurologic Features by Anjali Yadav, Chandrika Azad, Ravinder Kaur, Vishal Guglani, Seema Gupta and Sukanya Mitra in Journal of Child Neurology</p

Modulation of the Ligand-Field Anisotropy in a Series of Ferric Low-Spin Cytochrome <i>c</i> Mutants derived from Pseudomonas aeruginosa Cytochrome <i>c</i>-551 and Nitrosomonas europaea Cytochrome <i>c</i>-552: A Nuclear Magnetic Resonance and Electron Paramagnetic Resonance Study

Cytochromes of the c type with histidine−methionine (His-Met) heme axial ligation play important roles in electron-transfer reactions and in enzymes. In this work, two series of cytochrome c mutants derived from Pseudomonas aeruginosa (Pa c-551) and from the ammonia-oxidizing bacterium Nitrosomonas europaea (Ne c-552) were engineered and overexpressed. In these proteins, point mutations were induced in a key residue (Asn64) near the Met axial ligand; these mutations have a considerable impact both on heme ligand-field strength and on the Met orientation and dynamics (fluxionality), as judged by low-temperature electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectra. Ne c-552 has a ferric low-spin (S = 1/2) EPR signal characterized by large g anisotropy with gmax resonance at 3.34; a similar large gmax value EPR signal is found in the mitochondrial complex III cytochrome c1. In Ne c-552, deletion of Asn64 (NeN64Δ) changes the heme ligand field from more axial to rhombic (small g anisotropy and gmax at 3.13) and furthermore hinders the Met fluxionality present in the wild-type protein. In Pa c-551 (gmax at 3.20), replacement of Asn64 with valine (PaN64V) induces a decrease in the axial strain (gmax at 3.05) and changes the Met configuration. Another set of mutants prepared by insertion (ins) and/or deletion (Δ) of a valine residue adjacent to Asn64, resulting in modifications in the length of the axial Met-donating loop (NeV65Δ, NeG50N/V65Δ, PaN50G/V65ins), did not result in appreciable alterations of the originally weak (Ne c-552) or very weak (Pa c-551) axial field but had an impact on Met orientation, fluxionality, and relaxation dynamics. Comparison of the electronic fingerprints in the overexpressed proteins and their mutants reveals a linear relationship between axial strain and average paramagnetic heme methyl shifts, irrespective of Met orientation or dynamics. Thus, for these His-Met axially coordinated Fe(III), the large gmax value EPR signal does not represent a special case as is observed for bis-His axially coordinated Fe(III) with the two His planes perpendicular to each other

Image_2_Transition of Serotype 35B Pneumococci From Commensal to Prevalent Virulent Strain in Children.jpeg

In our community-based prospective cohort study in young children, we observed a significant increase in pneumococcal serotype 35B nasopharyngeal (NP) commensal colonization during the 2011–2014 timeframe, but these strains were not associated with disease. Beginning in 2015 and continuing through to the present, the serotype 35B virulence changed, and it became the dominant bacteria isolated and associated with pneumococcal acute otitis-media (AOM) in our cohort. We performed comparative analyses of 250 35B isolates obtained from 140 children collected between 2006 and 2019. Changes in prevalence, clonal-complex composition, and antibiotic resistance were analyzed. Seventy-two (29%) of 35B isolates underwent whole-genome sequencing to investigate genomic changes associated with the shift in virulence that resulted in increased rates of 35B-associated AOM disease. 35B strains that were commensals and AOM disease-causing were mainly associated with sequence type (ST) 558. Antibiotic concentrations of β-lactams and ofloxacin necessary to inhibit growth of 35B strains rose significantly (2006–2019) (p50 of penicillin and ofloxacin between the years 2006–2014 and 2015–2019 (p=0.007 and p2+ transporter, 6%); priA (DNA replication, 5%); and on the enzymic gene ldcB (LD-carboxypeptidase, 3%). Pneumococcal serotype 35B strains was a common NP commensal during 2010–2014. In 2015, a shift in increasing number of AOM cases occurred in young children caused by 35B, that was associated with changes in genetic composition and antibiotic susceptibility.</p