Determination of glucose oxidase activity by tyrosine fluorescence spectrophotometry

Abstract

A novel Fe2+/Tyr/H2O2 fluorescence reaction system has been established for the purpose of analyzing glucose oxidase activity. This system involves the catalysis of glucose oxidase on glucose to produce H2O2, which in turn oxidizes tyrosine to a highly fluorescent substance under the catalysis of Fe2+. The fluorescence intensity is subsequently employed to ascertain the enzymatic activity of glucose oxidase. The enzymatic oxidation reaction and tyrosine fluorescence reaction conditions were optimized based on the H2O2 standard curve equation. Direct fluorescence spectrophotometry was used to determine the activity range and detection limit of glucose oxidase, which were found to be 7.00 × 10−5–7.00 × 10−2 U/mL and 3.36 × 10−5 U/mL (Enzyme-like activity is 6.72 × 10−4 U/mL, The enzyme reaction time is 5 min), respectively, with a relative standard deviation of less than 3.2 %. This method has been successfully applied to determine the activity of glucose oxidase in food additives, with a recovery rate ranging from 96.00 % to 102.0 %.

Keywords

• Glucose oxidase
• Glucose
• Hydrogen peroxide
• Tyrosine
• Fluorophotometry