Mo nitrogenase is the primary source of biologically fixed nitrogen, making this system highly interesting for developing new, energy efficient ways of ammonia production. Although heavily investigated, studies of the active site of this enzyme have generally been limited to spectroscopic methods that are compatible with the presence of water and relatively low protein concentrations. One method of overcoming this limitation is through lyophilization, which allows for measurements to be performed on solvent free, high concentration samples. This method also has the potential for allowing efficient protein storage and solvent exchange. To investigate the viability of this preparatory method with Mo nitrogenase, we employ a combination of electron paramagnetic resonance, Mo and Fe K-edge X-ray absorption spectroscopy, and acetylene reduction assays. Our results show that while some small distortions in the metallocofactors occur, oxidation and spin states are maintained through the lyophilization process and that reconstitution of either lyophilized protein component into buffer restores acetylene reducing activity.
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http://dx.doi.org/10.1007/s00775-020-01838-4 | DOI Listing |
Anal Methods
January 2025
Lead Exposure Elimination Project, London, W10 4BP, UK.
Determining lead (Pb) concentrations in new paints using spectroscopic methods such as Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) requires technical expertise, consumables, equipment for method preparation, and instrumentation that can be cost prohibitive and difficult to maintain in low and middle-income countries (LMICs). Although portable X-ray Fluorescence (pXRF) analyzers are less expensive and simple to operate, their inaccuracy has limited their use to screening for the analysis of Pb in new, dried paint. To determine the limits of pXRF analyzers, new paint samples were purchased, dried, homogenized, and analyzed pXRF and ICP-OES.
View Article and Find Full Text PDFMed Chem
January 2025
Graduate School of NanoBio Sciences, Yokohama City University, 22-2, Seto, Kanazawa-Ku, Yokohama 236-0027, Japan.
Aim: There is an urgent need for new antimicrobial compounds with alternative modes of action for the treatment of drug-resistant bacterial and fungal pathogens.
Background: Carbohydrates and their derivatives are essential for biochemical and medicinal research because of their efficacy in the synthesis of biologically active drugs.
Objective: In the present study, a series of methyl α-D-mannopyranoside (MMP) derivatives (2-6) were prepared via direct acylation, and their biological properties were characterized.
This study investigates the modulations in the optical properties of cationic surfactant cetylpyridinium chloride (CPC) and hydrazine-mediated copper nanoclusters (CuNCs). By employing a bottom-up approach, we demonstrate the formation of blue-emitting CuNCs facilitated by CPC and hydrazine, where hydrazine acts both as a reducing and stabilizing agent. The optical properties of the CuNCs were systematically tuned by varying the chain length of the diamine, resulting in emissions ranging from blue to yellow.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata, West Bengal 700032, India.
Designing catalysts for the selective reduction of CO, resulting in products having commercial value, is an important area of contemporary research. Several molecular catalysts have been reported to facilitate the reduction of CO (both electrochemical and photochemical) to yield 2e/2H electron-reduced products, CO and HCOOH, and selective reduction of CO beyond 2e/2H is rare. This is partly because the factors that control the selectivity of CO reduction beyond 2e are not yet understood.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, 532 10, Czech Republic.
Radio frequency magnetron co-sputtering method employing GeTe and Sc targets was exploited for the deposition of Sc doped GeTe thin films. Different characterization techniques (scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction, atomic force microscopy, sheet resistance temperature-dependent measurements, variable angle spectroscopic ellipsometry, and laser ablation time-of-flight mass spectrometry) were used to evaluate the properties of as-deposited (amorphous) and annealed (crystalline) Ge-Te-Sc thin films. Prepared amorphous thin films have GeTe, GeTeSc, GeTeSc, GeTeSc and GeTeSc chemical composition.
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