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The Escherichia coli ChrR enzyme is an obligatory two-electron quinone reductase that has many applications, such as in chromate bioremediation. Its crystal structure, solved at 2.2 Å resolution, shows that it belongs to the flavodoxin superfamily in which flavin mononucleotide (FMN) is firmly anchored to the protein. ChrR crystallized as a tetramer, and size exclusion chromatography showed that this is the oligomeric form that catalyzes chromate reduction. Within the tetramer, the dimers interact by a pair of two hydrogen bond networks, each involving Tyr128 and Glu146 of one dimer and Arg125 and Tyr85 of the other; the latter extends to one of the redox FMN cofactors. Changes in each of these amino acids enhanced chromate reductase activity of the enzyme, showing that this network is centrally involved in chromate reduction.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3338774 | PMC |
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0036017 | PLOS |
Org Lett
September 2025
Guangdong Basic Research Center of Excellence for Aggregate Science, School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China.
The polymerization mechanism and the identification of key oligomer intermediates during the thermal condensation of benzoguanamine (BG) remain unclear. Herein, we report a novel mixed thermal condensation strategy using BG and a pre-synthesized dimer to selectively synthesize the trimer (BG) with a significantly enhanced yield. Comprehensive characterization techniques confirm the formation of a linear molecular structure for (BG).
View Article and Find Full Text PDFACS Nano
September 2025
Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States.
Achieving high performance nanoscale photonic functionalities remains extraordinarily challenging when using naturally derived biomaterials. The ability to manipulate ultrathin films of structural proteins─combined with photolithographic control of their polymorphism─unlocks a compelling route toward engineering biopolymer-based photonic crystals with precisely defined photonic bandgaps and reconfigurable structural colors. In this work, we describe a robust, water-based fabrication process for silk/inorganic hybrid one-dimensional (1D) photonic crystals that overcomes many of the conventional difficulties in ensuring reproducibility, uniformity, and reliability at the nanoscale.
View Article and Find Full Text PDFOrg Lett
September 2025
College of Chemistry and Materials Science, Key Laboratory of Chemical Biology of Hebei Province, Hebei University, Baoding, Hebei 071002, P. R. China.
Four novel coumarin-containing arenes bearing a [5]/[6]helicene unit (, , , and ) have been readily synthesized and structurally verified by X-ray crystallographic analysis. The chiral resolution of molecules , , and has enabled a detailed investigation of their chiroptical properties and the kinetics of enantiomerization, manifesting that the [6]helicenes and exhibit a more enhanced chiroptical response compared to [5]helicene .
View Article and Find Full Text PDFJ Colloid Interface Sci
September 2025
Faculty of Chemical Engineering, Kunming University of Science and Technology, Kunming 650093, China.
Encapsulation of non-noble bimetallic nanoparticles within a zeolite framework can improve the stability and accessibility of active sites, but the single microporous structure and poor metal stability decreased the catalytic performance of the catalyst. Here, 3D hierarchical ZSM-5 zeolite encapsulated NiCo nanoparticles (NiCo@3DHZ5) were synthesized by Bottom-up confined steam-assisted crystallization (SAC) one-pot hydrothermal method and applied to the hydrodeoxygenation of vanillin. A series of characterizations showed that highly stable alloyed NiCo nanoparticles were encapsulated in a framework of 3DHZ5, the strong metal-zeolite interactions resulted in highly dispersed NiCo nano-alloys facilitated hydrogen adsorption and spillover of active hydrogen atoms, and the 3D hierarchical structure promoted oxygenated substrate diffusion, the synergy interaction between the alloy particles confined in the 3DHZ5 pores and the acidic sites on the zeolite surface promoted the selective conversion of vanillin.
View Article and Find Full Text PDFFood Chem
September 2025
Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China. Electronic address:
Amino acid surfactants have garnered increasing attention as green and safe alternatives. Bioinspired by the melanogenesis pathway, this study developed a novel melanin-like amino acid surfactant with a melanin mimetic structure by conjugating glycine to o-quinone. Pterostilbene, a versatile natural monophenol, was oxidized to form o-quinone crystals by 2-iodoxybenzoic acid in a manner analogous to tyrosinase.
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