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Pyrazine is a kind of compound containing pyrazine ring structure, which has attracted the attention of researchers because of its special aroma and healthcare function. It is currently used in spices, pharmaceuticals, food additives, and other industries. Human serum albumin (HSA) is a transport and storage protein in the human circulatory system. Previous research reported that pyrazine can interact with albumin, but the interaction between pyrazine and HSA has not been reported. Consequently, this study is based on the multispectral method and molecular dynamics (MD) simulation, exploring the interaction between different pyrazines and HSA. The results show that the four pyrazines mainly quench the endogenous fluorescence of HSA through the static quenching mechanism. Molecular docking indicates that hydrophobic forces play a major role in the binding of pyrazines with HSA. At the same time, synchronous fluorescence spectroscopy, circular dichroism (CD), three-dimensional fluorescence spectroscopy, and resonance light scattering (RLS) showed that each pyrazine compound can change the conformation of HSA. MD simulation results show that the combination of four pyrazines and HSA can enhance the stability of HSA. Among them, 2,3,5,6-tetramethylpyrazine (TTMP) and 2,3,5-trimethylpyrazine (TMTP) binding is the most stable and the most unstable combination with HSA, respectively. In addition, the four pyrazines could affect the physiological activity of HSA. This study is of great significance to explore the mechanism of action of pyrazine compounds in vivo and can provide useful information for the application of pyrazine compounds in food. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Rationally developing efficient and durable bifunctional catalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for rechargeable zinc‐air batteries (ZABs). Herein, a bead‐like CoSe2@NC@NCNFs bifunctional catalyst was designed and fabricated by confining cubic CoSe2 nanoparticles to three‐dimensional (3D) porous MOFs‐derived nitrogen‐doped carbon (NC) and one‐dimensional (1D) N‐doped carbon nanofibers (NCNFs) through a facile encapsulate strategy. The 1D/3D continuous network structure contributes to the improvement of specific surface area and electronic conductivity, while the strong synergistic effect between CoSe2 sites and Co‐Nx‐C sites can effectively enhance electron/mass transfer and reduce the diffusion resistance. The as‐constructed CoSe2@NC@NCNFs catalyst exhibits high catalytic activity and stability toward ORR/OER with a high half‐wave potential of 0.80 V (vs. RHE) in ORR and a low overpotential of 280 mV at 10 mA·cm−2 in OER. More encouragingly, the rechargeable ZABs with CoSe2@NC@NCNFs cathode deliver high peak power densities (126.8 mW·cm−2), large specific capacities (763.1 mA·h·g−1), and robust charge‐discharge cycling stability over 240 cycles. This study provides a facile strategy for designing efficient bifunctional catalysts for rechargeable energy conversion applications. [ABSTRACT FROM AUTHOR]

Amino alcohols are important compounds that are widely used in the polymer and pharmaceutical industry, particularly when used as chiral scaffolds in organic synthesis. The hydroxylation of polyamide polymers may allow crosslinking between molecular chains through the esterification reactions of hydroxyl and carboxyl groups. Therefore, this may alter the functional properties of polyamide polymers. 2-hydroxycadaverine (2HyC), as a new type of chiral amino alcohol, has potential applications in the pharmaceutical, chemical, and polymer industries. Currently, 2HyC production has only been realized via pure enzyme catalysis or two-stage whole-cell biocatalysis, which faces great challenges for scale-up production. However, the use of a cell factory is very promising for the production of 2HyC in industrial applications. Here, we designed and constructed a promising artificial pathway in Escherichia coli for producing 2HyC from biomass-derived lysine. This biosynthesis route expands the lysine catabolism pathway and employs two enzymes to sequentially convert lysine into 2HyC. However, the catalytic activity of wild-type pyridoxal phosphate-dependent decarboxylase from Chitinophage pinensis (DCCp) toward 3-hydroxylysine is lower, resulting in the lower production of 2HyC. Thus, the higher catalytic activity of DCCp is desired for low-cost and expanded industrial applications of 2HyC. To improve the catalytic activity of DCCp, a mutant library of DCCp was first built using a semi-rational design. The Kcat/Km of mutant DCCp (R53D/V94I) increased by 63%. A titer of 359 mg/L 2HyC was produced in shake flasks, with a 2HyC titer increase of 54% compared to control strain ML101. The results show that the production of 2HyC was effectively increased through a semi-rational design strategy. These findings lay the foundation for the development and utilization of renewable resources to produce 2HyC in microorganisms via an efficient, green, and sustainable biosynthetic strategy for further industrial application. [ABSTRACT FROM AUTHOR]

To address the issue of surface enrichment of A-site ions in perovskite and the resulting suppression of catalytic activity, the La0.8Sr0.2Mn0.8Cu0.2O3 was modified by treatment with dilute nitric acid (2 mol/L) and dilute acetic acid (2 mol/L). The results show that the effect of dilute nitric acid treatment on the morphology and catalytic activity of the catalyst is more significant. The specific surface area of the catalyst after dilute nitric acid treatment (268.78 m2/g) is seven times higher than before treatment (37.55 m2/g). The low-temperature catalytic oxidation activity of HCHO of the catalyst after dilute nitric acid treatment is significantly improved, achieving a 50% HCHO oxidation efficiency at 80 °C, while the original sample requires 127 °C to achieve a 50% HCHO conversion. The excellent catalytic activity of the catalyst after dilute nitric acid treatment is related to its large specific surface area, high surface-active site density, and abundant Mn4+ ions. Stability and water resistance experiments show that the catalyst after dilute nitric acid treatment has excellent reaction stability and good water resistance ability. The mechanism of the formaldehyde oxidation reaction is that formaldehyde is first oxidized to a dioxymethylene (DOM) intermediate and DOM dehydrogenation reaction is responsible for the formation of formate species (HCOO-). [ABSTRACT FROM AUTHOR]