Superoxide dismutase: A comparison of rate constants

We describe a hydrogel glucose sensor with in vivo stability based on boronic acid-based fluorescence intensity, integrating two antioxidant enzymes, superoxide dismutase, and catalase

Henry J. Forman; Irwin Fridovich

2005

Scholarcy highlights

  • O2−was introduced, at a constant rate, into buffered aqueous solutions, either by mechanical infusion of KO2, dissolved in tetrahydrofuran, or by the in situ action of xanthine oxidase on xanthine plus oxygen. This O2− was allowed to react with ferricytochrome c or with tetranitromethane and the formation of the reaction products, ferrocytochrome c or nitroform, respectively, was monitored spectrophotometrically
  • The rate constant for the enzymatic dismutation of O2− by the copper and zinc containing enzyme from bovine erythrocytes was calculated from the known rate constants for the reaction of O2− with ferricytochrome c and with tetranitromethane and was found to be 2 × 109m−1 sec−1 at pH 7.8 and 8.5. This rate constant was obtained at steady-state concentrations of O2− in the 10−8m → 10−13m range and is in full agreement with the results of pulse radiolytic investigations which were performed at O2− concentrations in the 10−5m range
  • We describe a hydrogel glucose sensor with in vivo stability based on boronic acid-based fluorescence intensity, integrating two antioxidant enzymes, superoxide dismutase, and catalase. These protected the arylboronic acid from being degraded by hydrogen peroxide in vitro and preserved the boronic acid-based fluorescence intensity of the hydrogel glucose sensors in rats for 28 days. These antioxidant enzymes allowed the hydrogel glucose sensor attached to a homemade semi-implantable continuous glucose monitoring device to trace blood glucose concentrations in rats for 5 h with the accuracy required for clinical settings
  • Based on the mechanistic view described above, this review summarizes the mechanisms that may account for the excessive production of reactive oxygen species, the potential mechanistic roles of ROS that drive Nonalcoholic fatty liver disease progression, and therapeutic interventions that are related to oxidative stress
  • The best result was afforded by complex 1 with IC50 = 4.7 ± 1.0 μM, which corresponds to 10.2% of the native Cu,Zn-SOD enzyme activity
  • To achieve a deeper mechanistic understanding of how ROS are generated by complex III, we developed a mathematical model that successfully describes experimental data of complex III activity in various rat tissues, the production of ROS with and without antimycin and ROS generation depending on different values of the membrane potential ∆Ψ
  • The ability to catalyze multiple reactions in vivo expands the potential therapeutic use of the Mn porphyrins to disease models that are not superoxide dismutase based

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