The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
L Avigliano - One of the best experts on this subject based on the ideXlab platform.
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Dehydroascorbic Acid uptake in a human keratinocyte cell line (HaCaT) is glutathione-independent.
The Biochemical journal, 2000Co-Authors: I Savini, S Duflot, L AviglianoAbstract:Vitamin C plays an important role in neutralizing toxic free radicals formed during oxidative metabolism or UV exposure of human skin. This study was performed to investigate the mechanisms that regulate the homoeostasis of vitamin C in HaCaT cells by identifying the events involved in the transport and in the reduction of Dehydroascorbic Acid. Dehydroascorbic Acid accumulated to a greater extent and faster compared with ascorbic Acid; its transport appeared to be mediated by hexose transporters and was entirely distinct from ascorbic Acid transport. Dehydroascorbate Reductase activity was unaffected by glutathione depletion, although it was sensitive to thiol protein reagents. These observations, as well as the subcellular distribution of this enzymic activity and the cofactor specificity, indicate that thioredoxin Reductase and lipoamide dehydrogenase play an important role in this reduction process. HaCaT cells were able to enhance their Dehydroascorbic Acid Reductase activity in response to oxidative stress.
Gary W. Felton - One of the best experts on this subject based on the ideXlab platform.
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Antioxidant role of Dehydroascorbic Acid Reductase in insects
Biochimica et biophysica acta, 1993Co-Authors: Clinton B. Summers, Gary W. FeltonAbstract:Dehydroascorbic Acid Reductase, which catalyses the regeneration of ascorbic Acid from Dehydroascorbic Acid, is reported here to occur widely among insects. Due to the reported absence of glutathione peroxidase in insects and the generally low affinity of catalase for hydrogen peroxide, Dehydroascorbic Acid Reductase may play a pivotal role in the elimination of hydrogen peroxide in insects.
William W. Wells - One of the best experts on this subject based on the ideXlab platform.
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Identification of the Dehydroascorbic Acid Reductase and thioltransferase (Glutaredoxin) activities of bovine erythrocyte glutathione peroxidase.
Biochemical and Biophysical Research Communications, 1999Co-Authors: Michael P Washburn, William W. WellsAbstract:Bovine erythrocyte glutathione (GSH) peroxidase (GPX, EC 1.11.1.9) was examined for GSH-dependent dehydroascorbate (DHA) Reductase (EC 1.8.5.1) and thioltransferase (EC 1.8.4.1) activities. Using the direct assay method for GSH-dependent DHA Reductase activity, GPX had akcat(app) of 140 ± 9 min−1and specificity constants (kcat/Km(app)) of 5.74 ± 0.78 × 102M−1s−1for DHA and 1.18 ± 0.17 × 103M−1s−1for GSH based on the monomer Mrof 22,612. Using the coupled assay method for thioltransferase activity, GPX had akcat(app) of 186 ± 9 min−1and specificity constants (app) of 1.49 ± 0.14 × 103M−1s−1for S-sulfocysteine and 1.51 ± 0.18 × 103M−1s−1for GSH based on the GPX monomer molecular weight. GPX has a higher specificity constant for S-sulfocysteine than DHA, and both assay systems gave nearly identical specificity constants for GSH. The DHA Reductase and thioltransferase activities of GPX adds to the repertoire of functions of this enzyme as an important protector against cellular oxidative stress.
Mark Levine - One of the best experts on this subject based on the ideXlab platform.
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Purification, cloning and expression of Dehydroascorbic Acid-reducing activity from human neutrophils: identification as glutaredoxin.
Biochemical Journal, 1996Co-Authors: Jae B. Park, Mark LevineAbstract:Dehydroascorbic Acid-reducing activity in normal human neutrophil lysates was characterized and identified by activity-based purification and measurement of newly synthesized ascorbate by HPLC. The initial reducing activity was non-dialysable and could not be accounted for by the activity of glutathione as a reducing agent. The reducing activity was purified to homogeneity as an 11 kDa protein. The protein had a specific activity of 3 mumol/min per mg of protein and was glutathione dependent. Kinetic experiments showed that the protein had a K(m) for glutathione of 2.0 mM and a K(m) for Dehydroascorbic Acid of 250 microM. Dehydroascorbic Acid reduction by the purified protein was pH dependent and was maximal at pH 7.5. Peptide fragments from the purified protein were analysed for amino Acid sequence and the protein was identified as glutaredoxin. By using degenerate oligonucleotides based on the amino Acid sequence, glutaredoxin was cloned from a human neutrophil library. Expressed purified glutaredoxin displayed reducing activity and kinetics that were indistinguishable from those of native purified enzyme. Several approaches indicated that glutaredoxin was responsible for the most of the protein-mediated Dehydroascorbic Acid reduction in lysates. From protein purification data, glutaredoxin was responsible for at least 47% of the initial reducing activity. Dehydroascorbic Acid reduction was at least 5-fold greater in neutrophil lysates than in myeloid tumour cell lysates, and glutaredoxin was detected in normal neutrophil lysates but not in myeloid tumour cell lysates by Western blotting. Glutaredoxin inhibitors inhibited Dehydroascorbic Acid reduction in neutrophil lysates as much as 80%. These findings indicate that glutaredoxin plays a major role in Dehydroascorbic Acid reduction in normal human neutrophil lysates, and represent the first identification of Dehydroascorbic Acid Reductase in human tissue by activity-based purification.
I Savini - One of the best experts on this subject based on the ideXlab platform.
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Dehydroascorbic Acid uptake in a human keratinocyte cell line (HaCaT) is glutathione-independent.
The Biochemical journal, 2000Co-Authors: I Savini, S Duflot, L AviglianoAbstract:Vitamin C plays an important role in neutralizing toxic free radicals formed during oxidative metabolism or UV exposure of human skin. This study was performed to investigate the mechanisms that regulate the homoeostasis of vitamin C in HaCaT cells by identifying the events involved in the transport and in the reduction of Dehydroascorbic Acid. Dehydroascorbic Acid accumulated to a greater extent and faster compared with ascorbic Acid; its transport appeared to be mediated by hexose transporters and was entirely distinct from ascorbic Acid transport. Dehydroascorbate Reductase activity was unaffected by glutathione depletion, although it was sensitive to thiol protein reagents. These observations, as well as the subcellular distribution of this enzymic activity and the cofactor specificity, indicate that thioredoxin Reductase and lipoamide dehydrogenase play an important role in this reduction process. HaCaT cells were able to enhance their Dehydroascorbic Acid Reductase activity in response to oxidative stress.