Superoxide dismutase (SOD, EC 1.15.1.1) is an important metal-containing antioxidant enzyme that provides the first line of defense against toxic superoxide radicals by catalyzing their dismutation to oxygen and hydrogen peroxide. SOD is classified into four metalloprotein isoforms, namely, Cu/Zn SOD, Mn SOD, Ni SOD and Fe SOD. The structural models of soybean SOD isoforms have not yet been sol...

Polbax, a water-soluble extract of fresh pollen grains and pistils, was tested for its ability to influence the accumulation of lipofuscin (age pigment) in cultured neonatal rat cardiac myocytes. Exposure for 3 weeks to Polbax at concentrations of 0.1, 1.0 or 10 mg/L decreased lipofuscin accumulation morphometrically assayed using laser scanning microscopy images (green excitation light) of for...

The biosynthesis of riboflavin requires 1 equivalent of GTP and 2 equivalents of ribulose phosphate. The first committed reactions of the convergent pathway are catalyzed by GTP hydrolase II and 3,4-dihydroxy-2-butanone 4-phosphate synthase. The initial reaction steps afford 5-amino-6-ribitylaminopyrimidine 5'-phosphate, which needs to be dephosphorylated by a hitherto elusive hydrolase. The de...

In contrast to the NADPH oxidases Nox1 and Nox2, which generate superoxide (O(2)(·-)), Nox4 produces hydrogen peroxide (H(2)O(2)). We constructed chimeric proteins and mutants to address the protein region that specifies which reactive oxygen species is produced. Reactive oxygen species were measured with luminol/horseradish peroxidase and Amplex Red for H(2)O(2) versus L-012 and cytochrome c f...

Reactions of primary imidazolio-phosphides (“imidazolylidene-phosphinidenes”) with R2SnCl2 yield as main products spectroscopically detectable Lewis pairs which undergo base-induced dehydrochlorination in the presence excess dichlorostannane to afford zwitterionic chloride adducts distannylated imidazolio-phosphines. In contrast, reactions R3SnCl proceed under dismutation furnish mixtures conta...

This article describes the formation of reactive oxygen species as a result of the oxidation of dissolved sulfide by Fe(III)-containing sediments suspended in oxygenated seawater over the pH range 7.00 and 8.25. Sediment samples were obtained from across the coastal littoral zone in South Carolina, US, at locations from the beach edge to the forested edge of a Spartina dominated estuarine salt ...

Copper-zinc superoxide dismutase (SOD) is of fundamental importance to our understanding of oxidative damage. Its primary function is catalysing the dismutation of superoxide to O(2) and H(2)O(2). SOD also reacts with H(2)O(2), leading to the formation of a strong copper-bound oxidant species that can either inactivate the enzyme or oxidise other substrates. In the presence of bicarbonate (or C...

By sulfur substitution of the N-5 atom in flavins and flavocoenzymes a flavin analog is obtained, Sthiaflavin, which is found to be isoelectronic and isosteric with natural flavin in the fully reduced and half-reduced states, but not in the oxidized state. Among the three ‘redox shuttles’ characterizing the flavin system, viz. upper le-, lower leand 2eshuttle, only the second one is retained in...

Elicitation of cultured chickpea (Cicer arietinum L.) cells stimulates a signal transduction pathway leading to several rapid responses: (1) oxidative burst, (2) extracellular alkalinisation, (3) extracellular acidification, (4) transient K+ efflux, and (5) activation of defence related genes all within 2 hours. Induced genes are encoding acidic and basic chitinases, a thaumatin-like protein an...

The thyroid plasma membrane contains a Ca2(+)-regulated NADPH-dependent H2O2 generating system which provides H2O2 for the thyroid peroxidase-catalyzed biosynthesis of thyroid hormones. The plasma membrane fraction contains a Ca2(+)-independent cytochrome c reductase activity which is not inhibited by superoxide dismutase. But it is not known whether H2O2 is produced directly from molecular oxy...