Oscillations in the concentration of divalent ions Cd(2+), Ca(2+), Zn(2+), Co(2+) and Ni(2+) are induced by adding these species to the BrO(3)(-)-SO(3)(2-) chemical oscillator in a flow reactor. Producing periodic pulses in the concentrations of these non-redox ions extends our earlier approach to generating forced periodic behavior. Instead of driving pH-dependent equilibrium reactions of the ...

Ethane formation, as a measure of lipid peroxidation, was studied in spinach (Spinacia oleracea L.) chloroplasts exposed to sulfite. Ethane formation required sulfite and light, and occurred with concomitant oxidation of sulfite to sulfate. In the dark, both ethane formation and sulfite oxidation were inhibited. Ethane formation was stimulated by ferric or ferrous ions and inhibited by ethylene...

Exposure to (bi)sulfite (HSO3-) and sulfite (SO32-) has been shown to induce a wide range of adverse reactions in sensitive individuals. Studies have shown that peroxidase-catalyzed oxidation of (bi)sulfite leads to formation of several reactive free radicals, such as sulfur trioxide anion (.SO3-), peroxymonosulfate (-O3SOO.), and especially the sulfate (SO4. -) anion radicals. One such peroxid...

Thiobacillus thiooxidans cells oxidized elemental sulfur to sulfite, with 1 mol of O(2) consumption per mol of sulfur oxidized to sulfite, when the oxidation of sulfite was inhibited with 2-n-heptyl-4-hydroxyquinoline N-oxide.

In phototrophic sulfur bacteria, sulfite is a well-established intermediate during reduced sulfur compound oxidation. Sulfite is generated in the cytoplasm by the reverse-acting dissimilatory sulfite reductase DsrAB. Many purple sulfur bacteria can even use externally available sulfite as a photosynthetic electron donor. Nevertheless, the exact mode of sulfite oxidation in these organisms is a ...

The biochemical basis for sulfite accumulation by sulfate-using revertants of Salmonella pullorum was determined. All of the sulfate-using mutants isolated from wild-type S. pullorum accumulated sulfite when grown at 37 but not at 25 C. The specific activity of reduced nicotinamide adenine dinucleotide (NADPH)-dependent sulfite reductase (H2S-NADP oxidoreductase, EC 1.8.1.2) and of reduced meth...

Urocanase is inactivated in vivo and is reactivated by ultraviolet radiation. The chemistry of this photoregulation of urocanase was studied. Purified enzyme was inactivated by 25 pM sulfite (tl,z, 15 min). Dialyzed sulfite-treated inactive enzyme was photoactivatable. The activity can be cycled repeatedly by alternate ultraviolet light and sulfite treatments. Active enzyme binds 5 times more [...