Acid xylanase (xylanase) is an enzyme whose main function is to degrade xylan in lignocellulose, and is used in the production of feed, food, alcohol and other industries. The following is the assay method for the activity of acid xylanase preparations:
Phenol-sulfuric acid method
step:
Prepare the phenol-sulfuric acid reagent: add 0.5 g of phenol into 50 mL of concentrated sulfuric acid, stir well and cool to room temperature;
Prepare the standard curve: take a certain concentration of xylan standard solution, add an appropriate amount of phenol-sulfuric acid reagent, mix well, measure the absorbance at a wavelength of 280 nm, and prepare a series of standard curves with different concentrations;
Take a certain amount of acid xylanase sample, add an appropriate amount of xylan substrate, adjust the pH to the optimum working pH, add phenol-sulfuric acid reagent after incubation for a certain period of time, and measure the absorbance at a wavelength of 280 nm after mixing;
The activity in the acid xylanase samples was calculated according to the standard curve.
3,5-Dinitrosalicylic acid method
step:
Prepare 3,5-dinitrosalicylic acid reagent: Dissolve 3,5-dinitrosalicylic acid and sodium hydroxide in ethanol respectively, mix and filter to obtain the reagent solution;
Prepare the standard curve: take a certain concentration of xylan standard solution, add an appropriate amount of 3,5-dinitrosalicylic acid reagent, mix well, measure the absorbance at a wavelength of 400 nm, and prepare a series of standard curves with different concentrations;
Take a certain amount of acid xylanase sample, add an appropriate amount of xylan substrate, adjust the pH to the optimum working pH, add 3,5-dinitrosalicylic acid reagent after incubation for a certain period of time, mix well Absorbance was measured at 400 nm;
The activity in the acid xylanase samples was calculated according to the standard curve.
The above are two commonly used acid xylanase activity assay methods, and
