Catalase catalyzes the decomposition of hydrogen peroxide to water and oxygen. The main role of this enzyme is to prevent cell damage caused by reactive oxygen species (ROS). However, endogenous catalase is sensitive to high temperature and possesses limited activity. To satisfy requirements for this critical bottleneck, in this work, we improved the thermo-stability of a heme-catalase (KatX2) from a high oxidative stress resistance Bacillus pumilus ML413 through the construction of a disulfide bond between S286C and D289C. After the site-directed mutagenesis targeting the disulfide bond between S286C and D289C into the wild-type catalase, a potential improvement of thermo-stability half-life at 60 °C was increased by 48 min compared to the wild-type half-life. Unexpectedly, a catalytic efficiency of KatX2 S286C/D289C mutant was increased by 40% when compared to the wild-type KatX2. More importantly, this unprecedented highly stable KatX2 recombinant mutant S286C/D289C exhibits higher catalytic efficiency and thermo-stability with no change on the catalase secondary structure. Thus, this rational design based KatX2 could be adopted as a potential biocatalyst in industry.
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http://dx.doi.org/10.1016/j.enzmictec.2018.08.002 | DOI Listing |
J Org Chem
January 2025
Technical Institute of Fluorochemistry (TIF), School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
The direct cross-couplings of aryl nonaflates with aryl bromides could be successfully accomplished by utilizing nickel as the catalyst, magnesium as the metal mediator, and lithium chloride as the additive. The reactions proceeded efficiently in THF at room temperature to produce the desired biaryls in moderate to good yields, showing both a reasonable substrate scope and functional group tolerance. Additionally, an equally good performance could be realized when the reaction was subjected to scale-up synthesis.
View Article and Find Full Text PDFRev Sci Instrum
January 2025
Institute for Physical Chemistry, University of Göttingen, 37077 Göttingen, Germany.
Surface science instruments require excellent vacuum to ensure surface cleanliness; they also require control of sample temperature, both to clean the surface of contaminants and to control reaction rates at the surface, for example, for molecular beam epitaxy and studies of heterogeneous catalysis. Standard approaches to sample heating within high vacuum chambers involve passing current through filaments of refractory metals, which then heat the sample by convective, radiative, or electron bombardment induced heat transfer. Such hot filament methods lead to outgassing of molecules from neighboring materials that are inadvertently heated; they also produce electrons and ions that may interfere with other aspects of the surface science experiment.
View Article and Find Full Text PDFJ Agric Food Chem
January 2025
Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China.
Steviol glycosides (SGs) are highly valued for their sweetness, safety, and zero calories, but their bitter taste and low solubility limit their application. Modifying glycosyl units is a promising strategy to improve sensory qualities. In this study, we identified the enzyme UGT94E13 through phylogenetic analysis and enzyme screening, which catalyzes the glycosylation of rebaudioside M2 (Reb M2) at the C-13 position, producing the novel β-1,6--glycosylated product rebaudioside M9 (Reb M9).
View Article and Find Full Text PDFNanoscale Adv
January 2025
Synthetic Organic Chemistry Laboratory, Department of Chemistry, MLSU Udaipur-313001 Rajasthan India
Catalysis plays a vital role in green chemistry by improving process efficiency, reducing waste, and minimizing environmental impact. A biochar-modified g-CN·SOH (BCNSA) catalyst was developed using biochar derived from amla seed powder and CNSA. CNSA was synthesized the reaction of g-CN with chlorosulfonic acid.
View Article and Find Full Text PDFAcc Mater Res
January 2025
Department of Chemistry, University of Manchester, Manchester M13 9PL, U.K.
Methane (CH), which is the main component of natural gas, is an abundant and widely available carbon resource. However, CH has a low energy density of only 36 kJ L under ambient conditions, which is significantly lower than that of gasoline (. 34 MJ L).
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