3results about How to "Improves pH stability" patented technology

This invention belongs to the technical field of bactericide residue analysis and determination in plant-derived foods, specifically relating to a method for detecting isobutylethoxyquinoline and its metabolites in plant-derived foods. The method includes extraction with acetonitrile under citrate conditions, followed by purification with C18 (25 mg), PAX (25 mg), and XFM64 (nitrogen-doped multi-walled carbon nanotubes, 10 mg) adsorbents. Chromatographic separation is performed using a C18 column with methanol-2 mmol / L ammonium acetate (containing 0.1% formic acid) as the mobile phase, isocratic elution at a flow rate of 0.40 mL / min, electrospray ionization (ESI+), and detection in multiple reaction monitoring (MRM) mode. This invention is simple to operate, has high pretreatment efficiency, and its precision and recovery rate meet the regulatory residue limit monitoring requirements. It is suitable for the simultaneous determination of isobutylethoxyquinoline and its metabolites in plant-derived foods.

This invention discloses a method for preparing recombinant dextranase from Chaetomium globosum and its uses. The amino acid sequence of the recombinant dextranase is shown in SEQ ID NO.2 or SEQ ID NO.4, and the nucleotide sequence of its encoding gene is shown in SEQ ID NO.1 or SEQ ID NO.3. The optimal pH of the recombinant dextranase is 4.5-7.0, and the optimal reaction temperature is 45-60℃. + K + and Ca 2+ It has an activating effect on enzyme activity, Mg 2+ NH4 + and Mn 2+ It had no significant effect on enzyme activity, Fe 3+ Zn 2+ Cu 2+ and Co 2+ It has an inhibitory effect on enzyme activity. Furthermore, this enzyme exhibits excellent pH stability, good thermal stability, and anti-interference ability, making it well-suited to the application requirements of the food, pharmaceutical, and chemical industries.

The application discloses a method for immobilizing transaminase by cross-linking-adsorption, and immobilized enzyme and application thereof. The application adopts the adsorption-cross-linking method, and through screening of an immobilization method and optimization of key process parameters of immobilization, the prepared immobilized cell enzyme activity reaches 25.31 U / mg, and the enzyme activity recovery rate reaches 95.88%, which is obviously superior to traditional embedding methods or single adsorption methods, and effectively reduces enzyme activity loss in the immobilization process. The method directly uses whole cells, and does not need an enzyme purification step. Diatomite is widely available and low in price, and the modification and immobilization conditions are mild, the operation is simple, and the method is easy to scale up, so the method has a good industrial application prospect.