ascorbic-acid and 1-anilino-8-naphthalenesulfonate
ascorbic-acid has been researched along with 1-anilino-8-naphthalenesulfonate* in 2 studies
Other Studies
2 other study(ies) available for ascorbic-acid and 1-anilino-8-naphthalenesulfonate
Article | Year |
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Inactivation of phosphorylated rat tyrosine hydroxylase by ascorbate in vitro.
Tyrosine hydroxylase activity is reversibly controlled by the actions of several protein kinases. Previous studies showed that, following phosphorylation by protein kinase A, physiological concentrations of ascorbate irreversibly inactivate tyrosine hydroxylase. Several studies were performed to establish the mechanism of inactivation. We found that inactivation occurred under oxygen-free conditions. The results of this and other experiments suggest that oxygenated species such as superoxide or hydrogen peroxide were not required for inactivation by ascorbate. Inhibition of tyrosine hydroxylase by low concentrations of ascorbate raised the question concerning the mechanism for maintaining enzyme activity under physiological conditions. We report that tyrosine, N alpha-methyl tyrosine, 3-iodotyrosine, and phenylalanine protected the phosphorylated enzyme against ascorbate inactivation. Catecholamines (dopamine, norepinephrine, and some of their analogues) also protected the enzyme against ascorbate inactivation. We performed studies to assess conformational changes of tyrosine hydroxylase by measuring the extrinsic fluorescence using 8-anilino-1-naphthalenesulfonic acid as a reporter group. Phosphorylation of tyrosine hydroxylase by protein kinase A decreased the extrinsic fluorescence. Treatment of tyrosine hydroxylase with ascorbate produced a further decrease in fluorescence. These results provide evidence for conformational changes following these treatments. In contrast to extrinsic fluorescence, the circular dichroic spectrum of tyrosine hydroxylase failed to change following phosphorylation by protein kinase A or inhibition by ascorbate. The spectrum was consistent with a secondary structure of tyrosine hydroxylase with 55% alpha helix, 20% beta sheet, 2% beta turn, and 23% random coil. Topics: Amino Acid Sequence; Anilino Naphthalenesulfonates; Animals; Ascorbic Acid; Circular Dichroism; Dopamine; Free Radical Scavengers; Free Radicals; Molecular Sequence Data; Oxygen; PC12 Cells; Phosphorylation; Rats; Spectrometry, Fluorescence; Tyrosine; Tyrosine 3-Monooxygenase | 1993 |
Effects of lipid peroxidation on surface charge density of the porcine intestinal brush-border membranes.
The effects of lipid peroxidation on the surface charge density of the porcine intestinal brush-border membranes were studied using an oxygen-radical-generating system consisting of ascorbic acid, ferrous ion and tert-butyl hydroperoxide (tert-BuOOH). Changes in the membrane surface charge density were monitored using a fluorescent dye, 8-anilino-1-naphthalenesulfonate (ANS). The incubation of the membranes with ascorbic acid/Fe2+/tert-BuOOH resulted in a decrease of the fluorescence intensity of the ANS-membrane complex with a red-shift in the emission maximum, depending on the hydroperoxide concentration and the incubation time. The kinetic studies on ANS-binding showed that the apparent dissociation constant of ANS-membrane complex decreased by treatment with ascorbic acid/Fe2+/tert-BuOOH. Similar results were also obtained by treatment of the membranes with other oxidizing systems, hematin/tert-BuOOH and dipyridyl/Fe2+/tert-BuOOH. These results proposed the possibility that lipid peroxidation of the membranes causes an increase of the positive charge on the membrane surface. The results of the dependence of the ionic strength with increasing KCl concentrations in the medium upon the ANS-binding affinity for the membranes further supported this interpretation. Topics: Anilino Naphthalenesulfonates; Animals; Ascorbic Acid; Ferrous Compounds; Free Radical Scavengers; Intestine, Small; Kinetics; Lipid Peroxidation; Microvilli; Peroxides; Potassium Chloride; Spectrometry, Fluorescence; Surface Properties; Swine; tert-Butylhydroperoxide | 1993 |