It has long been established by Khan that the superoxide anion, O(2) (-), generates singlet oxygen, O(2) (1)Delta(g), during dismutation. Auranofin, gold-phosphine thiols, beta-Carotene, and metal-sulfur compounds can rapidly quench singlet O(2). The quenching of the O(2) (1)Delta(g), which exists at 7752 cm(-1) above the ground state triplet, may be due to the direct interaction of the singlet...

product containing a catechol group with an a ,b-unsaturated carboxylic acid chain (Fig. 1), is a widespread phenolic acid, naturally found in many agricultural products such as fruits, vegetables, wine, olive oil, and coffee. Caffeic acid has been reported to possess a wide spectrum of biological effects such as antioxidant activity, inhibition of enzyme activities (lipoxygenase, glutathione S...

Hyperhomocysteinemia (hHcys) is an important pathogenic factor contributing to the progression of end-stage renal disease. Recent studies have demonstrated the implication of nicotinamide adenine dinucleotide phosphate oxidase-mediated NLRP3 inflammasome activation in the development of podocyte injury and glomerular sclerosis during hHcys. However, it remains unknown which reactive oxygen spec...

Superoxide dismutases (SODs) are metalloproteins that catalyze the dismutation of superoxide radicals to hydrogen peroxide and oxygen. The enzyme is ubiquitous in aerobic organisms where it plays a major role in defense against oxygen radical-mediated toxicity. In plants, environmental adversity often leads to the increased generation of reduced oxygen species and, consequently, SOD has been pr...

Most of the oxygen consumed by aerobic organisms is reduced to water by the enzyme cytochrome c oxidase in the terminal reaction of the mitochondrial respiratory chain. Since oxygen in the ground state is in a triplet configuration (with two unpaired electrons in the outer shell) its reduction to water must occur in four consecutive one-electron steps. Some of the partially reduced oxygen inter...

Plant ascorbate peroxidases (APXs), enzymes catalyzing the dismutation of H2O2 into H2O and O2, play an important role in reactive oxygen species homeostasis in plants. The rice genome has eight OsAPXs, but their physiological functions remain to be determined. In this report, we studied the function of OsAPX2 gene using a T-DNA knockout mutant under the treatment of drought, salt and cold stre...

Mutations often have drastically different effects in different genetic backgrounds; understanding a gene's biological function then requires an understanding of its interaction with genetic diversity. The antioxidant enzyme cytosolic copper/zinc superoxide dismutase (cSOD) catalyzes the dismutation of the superoxide radical, a molecule that can induce oxidative stress if its concentration exce...

Control of the intraphagosomal pH in neutrophils may be of importance in creating a microbicidal environment by regulating the activity of the O2-.-generating NADPH oxidase and the lysosomal enzymes discharged into this compartment. In this study, we examined the proton stoichiometry associated with the primary enzymatic reaction underlying the respiratory burst. A preparation of the neutrophil...

The reduction of cytochrome c by xanthine oxidase and the competitive inhibition of this process by carbonic anhydrase and by myoglobin have been studied by kinetic and by equilibrium binding methods. Carbonic anhydrases isolated from bovine and from human erythrocytes differed strikingly in their ability to inhibit competitively the reduction of cytochrome c. The KS for cytochrome c was a func...

To delineate further the role of superoxide dismutase (SOD) in red blood cell (RBC) oxidant defense, normal human erythrocytes were osmotically lysed and resealed in the presence of varying concentrations of exogenous SOD. This resulted in a dose-dependent increase in SOD activity in the resealed erythrocytes while maintaining nearly normal RBC hemoglobin concentration (less than 10% decrease f...