Degradation of phenylalanine in the presence of hydrogen peroxide.

UV-irradiation of phenylalanine by 253.7 nm light in the presence of hydrogen peroxide formed 5 ninhydrin reactive products and ammonia. Four of them were identified as aspartic acid, serine, alanine and lysine.     

The action of hydrogen peroxide on amino acids in presence of iron salts and its bearing on photolysis of amino acids

Zusammenfassung Es wurde der Abbau von Aminosäuren durch Wasserstoffsuperoxyd in Gegenwart von Eisensalzen untersucht. Papierchromatographische Analyse zeigte, dass dabei aus-Aminobuttersäure-Alanin und Glycin, aus-Alanin und Serin Glycin entsteht. Die Bildung von-Alanin und Asparaginsäure aus-Aminobuttersäure und von Asparaginsäure aus Glutaminsäure konnte ebenfalls festgestellt werden. Diese Resultate werden in Zusammenhang gebracht mit dem Mechanismus der Photolyse von Aminosäuren in Gegenwart von TiO₂.     

The effect of hydrogen peroxide on the cyclin D expression in fibroblasts

Activation of mitogen-activated protein (MAP) kinase is essential for cyclin D1 expression and provides a link between mitogenic signalling and cell cycle progression. Hydrogen peroxide (H₂ O₂ ) activates MAP kinase; however, it is not known whether this leads to cyclin D expression. Sustained expression of cyclin D1 and D2 was observed when Her14 fibroblasts were incu-bated with 3 mM or higher H₂ O₂ concentrations. Similar results were obtained when cells were incubated in the presence of serum (FCS). However, the sustained expres-complex sion of cyclin D1 and D2 upon H₂ O₂ treatment was not due to the MAP kinase pathway, because MAP kinase kinase inhibitors did not inhibit cyclin D expression. Furthermore, cyclin D1 and D2 levels remained constant even after addition of a protein synthesis inhibitor, indicating that the effect of H₂ O₂ was not due to induction of protein synthesis. These results indicate that H₂ O₂ reversibly inhibits the ubiquitin-proteasome dependent degra-dation of cyclin D1 and D2, probably by transiently in-hibiting ubiquitination and/or the proteasome. Received 12 March 2001; received after revision 5 April 2001; accepted 9 April 2001     

Chronic hydrogen peroxide intake and peroxide metabolizing enzyme activities in some tissues of mice and rats

Summary Chronic daily intake of 0.5% H₂O₂ in drinking water decreased Se-dependent glutathione peroxidase (Se-GSHPx) activity in rat skeletal muscle, kidney and liver. Non-Se GSHPx activity decreased in kidney. Deprivation of drinking water decreased Se-GSHPx activity in kidney and non-Se GSHPx activity in kidney and liver. H₂O₂ intake decreased activity of catalase in rat skeletal muscle. H₂O₂ intake or water deprivation caused no changes in these enzyme activities in mice.     

Chronic hydrogen peroxide intake and peroxide metabolizing enzyme activities in some tissues of mice and rats

Chronic daily intake of 0.5% H2O2 in drinking water decreased Se-dependent glutathione peroxidase (Se-GSHPx) activity in rat skeletal muscle, kidney and liver. Non-Se GSHPx activity decreased in kidney. Deprivation of drinking water decreased Se-GSHPx activity in kidney and non-Se GSHPx activity in kidney and liver. H2O2 intake decreased activity of catalase in rat skeletal muscle. H2O2 intake or water deprivation caused no changes in these enzyme activities in mice.     

In vivo generation of hydrogen peroxide from 6-hydroxydopamine

Zusammenfassung Es gelang, die Erythrocytenkatalase der Maus durch Injektion von 6-Hydroxydopamin und in Gegenwart von 3-Amino-1,2,4-triazol zu hemmen, was auf die Wasserstoffperoxyd-Entwicklung hinweist und mit der Rolle des H₂O₂ bei der Degeneration der Nervenenden durch 6-Hydroxydopamin in Einklang steht.     

The oxidation of glutathione with formic acid and hydrogen peroxide

Zusammenfassung Durch Oxydation von Glutathion mit Wasserstoffsuperoxid in Ameisensäure wurde Glutathion-dihydrosulfoxid erhalten. Glutathion-sulfoxid, N-Acetylglutathion und assoziiertes (reversibel polymerisiertes) Glutathion wurden als Vergleichssubstanzen erstmalig hergestellt.

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This work was supported in part by funds of the U.S.P.H.S.     

Possible effect of radiation produced hydrogen peroxide on post-irradiation aversion in mice

Zusammenfassung Es wird gezeigt, dass röntgenbestrahlte Mäuse Saccharin- und Sucrose-Lösungen gleicherweise vermeiden wie Lösungen, denen minimale Mengen von H₂O₂ zugesetzt wurden. Es wird angenommen, dass der Effekt auf der radiolytischen Produktion von H₂O₂ in der Lösung zurückzuführen ist.

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This work was supported in part by Grant No. 2-46-33-90-3-10 from The University of Illinois Foundation.     

Effect of hydrogen peroxide on the binding of Merocyanine 540 to human erythrocytes

The fluorescent dye Merocyanine 540 (MC540) is often used as a probe to monitor the molecular packing of phospholipids in the outer leaflet of biomembranes. In a previous study we showed that the increased staining of erythrocytes with a perturbed membrane structure was mainly due to an increase in the fluorescence yield of cell-bound MC540, rather than to an increase of the number of bound molecules. Erythrocytes and ghosts exposed to continuous fluxes of H₂O₂ exhibited pronounced lipid peroxidation. Further, red blood cells subjected to this form of oxidative stress also showed increased staining with MC540. It appeared that this was caused by a strong increase in binding of MC540, together with a slight red shift of the fluorescence emission maximum and a small increase in the fluorescence yield of bound MC540. The changed MC540 binding characteristics were not observed when lipid peroxidation was suppressed by the presence of the antioxidant BHT in the incubation medium. However, open ghosts exposed to H₂O₂ showed no increase of MC540 binding, excluding a direct involvement of lipid peroxidation. Measurement of fluorescence emission spectra and gel filtration studies showed that MC540 can bind to H₂O₂-exposed hemoglobin. Experiments with erythrocytes lysed in hypotonic medium after exposure to H₂O₂ revealed that peroxidation of lipids with H₂O₂ induced a non-specific permeabilization of the plasma membrane to MC540, thereby allowing MC540 to bind to the oxidatively denatured, more hydrophobic hemoglobin. These results indicate that conclusions about packing of phospholipids in the outer leaflet of the membrane based on increased MC540-staining should be drawn with care. Received 27 September 1996; received after revision 5 November 1996; accepted 27 November 1996