After SO(2) has entered leaves of spinach (Spinacia oleracea) through open stomata and been hydrated in the aqueous phase of cell walls, the sulfite formed can be oxidized to sulfate by an apoplastic peroxidase that is normally involved in phenol oxidation. The oxidation of sulfite is competitive with the oxidation of phenolics. During sulfite oxidation, the peroxidase is inhibited. In the abse...

Sulfite has been identified as an essential metabolite by means of growth studies using a chemically-defined, protein-free medium for culture of human peripheral lymphocytes. Sulfite reduced the amount of cysteine required for optimum growth by at least four-fold. In some subjects, sulfite stimulated growth even in the presence of optimal amounts of cysteine indicating that lymphocytes of some ...

Milk xanthine oxidase can catalyze the reduction of oxygen, cytochrome c, nitrate, ferricyanide, and various quinones and dyes by many aldehydes and purines. When acting upon its substrates, this enzyme can also initiate the aerobic oxidation of sulfite (1, 2) and induce the chemiluminescence of lucigenin and of luminol (3, 4). The reduction of cytochrome c by milk xanthine oxidase has been the...

A wide range of microorganisms was tested to determine their sensitivity to low concentrations of bisulfite-sulfite and nitrite, solubility products of SO2 and NO2, respectively. Photosynthesis by blue-green algae (cyanobacteria) was more strongly inhibited by 0.1 mM bisulfite-sulfite and 1 mM nitrite at pH 6.0 than photosynthesis by eucaryotic algae and respiration of bacteria, fungi, and prot...

The DMSO reductase family consists of proteins that catalyze oxygen atom transfer reactions. These proteins are characterized by a mononuclear Mo center that is ligated by one or two molybdopterin cofactors (through the two thiolates). DMSO reductase itself is ligated by two molybdopterin cofactors and catalyzes the reduction of dimethyl sulfoxide to dimethyl sulfide. This reaction is important...

Many hybrid proline-rich protein (HyPRP) genes respond to biotic and abiotic stresses in plants, but little is known about their roles other than as putative cell-wall structural proteins. A HyPRP1 gene encodes a protein with proline-rich domain, and an eight-cysteine motif was identified from our previous microarray experiments on drought-tolerant tomato. In this study, the expression of the H...

A simple 4-hydroxynaphthalimide-derived colorimetric and ratiometric fluorescent probe (1) containing a receptor of levulinate moiety was designed and synthesized to monitor sulfite. Probe 1 could quantificationally detect sulfite by a ratiometric fluorescence spectroscopy method with high selectivity and sensitivity. Specially, probe 1 exhibited a 100 nm red-shifted absorption spectrum along w...

One is used to considering sulfite oxidation as part of a lithotrophic process (e.g. SorAB or Sox system), much of which involves neutral or ionic inorganic sulfur species on the outer surface of the cytoplasmic membrane. In contrast, the processes referred to in this chapter involve organic compounds, which (1) include a highly stable sulfonate substituent (C−SO 3 ), (2) are involved in the or...

Plant NiR (nitrite reductase) and SiR (sulfite reductase) have common structural and functional features. Both enzymes are generally distinguished in terms of substrate specificity for nitrite and sulfite. The genome of Cyanidioschyzon merolae, a unicellular red alga living in acidic hot springs, encodes two SiR homologues, namely CmSiRA and CmSiRB (C. merolae sulfite reductases A and B), but n...

An ssu2 mutation in Saccharomyces cerevisiae, previously shown to cause sulfite sensitivity, was found to be allelic to GRR1, a gene previously implicated in glucose repression. The suppressor rgt1, which suppresses the growth defects of grr1 strains on glucose, did not fully suppress the sensitivity on glucose or nonglucose carbon sources, indicating that it is not strictly linked to a defect ...