Mn(II)–sodium dodecyl sulphate complex mimic enzyme-catalyzed fluorescence quenching of Pyronine B by hydrogen peroxide Original Research Article

Mn(II)–sodium dodecyl sulphate complex (Mn(II)–SDS) is used to mimic the active group of peroxidase. The catalytic characteristic of this mimic enzyme catalyst in the oxidation reaction of fluorescence substrate, tetraethyldiaminoxanthyl chloride (Pyronine B (PB)), with hydrogen peroxide has been studied. The experimental results show that Mn(II)–SDS complex has similar catalytic activity that of peroxidase. The steady-state catalytic rate depends upon mimic enzyme and substrate concentrations, and the Michaelis–Menten parameters Km, Vmax and Kcat are 7.6×10−6 M, 7.9×10−7 M s−1 and 7.9 s−1, respectively. The catalytic activity of Mn(II)–SDS complex is compared with those of HRP and Hemin. Though the catalytic activity of Mn(II)–SDS complex is 15.9% of that of HRP, it can catalyze the oxidation reaction of PB with hydrogen peroxide lead to fluorescence quenching of PB. Under optimum conditions, linear relationship between fluorescence quenching F0/F and concentration of H2O2 is in the range of (0.0–3.6) × 10−7 M. The detection limit is determined to be 3.0×10−9 M. By coupling this mimic catalytic reaction with the catalytic reaction of glucose oxidase (GOD), glucose can be detected. Linear relationship between F0/F and concentration of glucose is in the range of (0.0–1.4) × 10−7 M. The detection limit is determined to be 4.2×10−9 M. This method is applied to the determination of glucose in human serum and the results are in good agreement with the phenol-4-aminoantipyrine (4-AAP).