دورية أكاديمية
Oxidation of delta-ALA-D and DTT mediated by ascorbic acid: modulation by buffers depends on free iron.
| العنوان: | Oxidation of delta-ALA-D and DTT mediated by ascorbic acid: modulation by buffers depends on free iron. |
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| المؤلفون: | Rocha JB; Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil. jbtrocha@yahoo.com.br, Lissner LA, Puntel RL, Fachinetto R, Emanuelli T, Nogueira CW, Soares FA |
| المصدر: | Biological & pharmaceutical bulletin [Biol Pharm Bull] 2005 Aug; Vol. 28 (8), pp. 1485-9. |
| نوع المنشور: | Journal Article; Research Support, Non-U.S. Gov't |
| اللغة: | English |
| بيانات الدورية: | Publisher: Pharmaceutical Society of Japan Country of Publication: Japan NLM ID: 9311984 Publication Model: Print Cited Medium: Print ISSN: 0918-6158 (Print) Linking ISSN: 09186158 NLM ISO Abbreviation: Biol Pharm Bull Subsets: MEDLINE |
| أسماء مطبوعة: | Original Publication: Tokyo : Pharmaceutical Society of Japan, c1993- |
| مواضيع طبية MeSH: | Ascorbic Acid/*chemistry , Dithiothreitol/*metabolism , Iron/*chemistry , Porphobilinogen Synthase/*metabolism, Buffers ; Oxidation-Reduction |
| مستخلص: | Ascorbic acid (AA) is one of the most important endogenous reducing agents and can participate in a variety of cellular events. In vitro, AA can act as a potent oxidant agent in the presence of free metals, promote modifications in protein structures and form reactive oxygen species during its oxidation. We have observed that AA (above 6 mmol/l) inactivates delta-aminolevulinate dehidratase (delta-ALA-D), a sulfhydryl-containing enzyme and that the inhibitory action was considerably decreased when 3-morpholinepropanesulfonic acid buffer (MOPS - pH: 6.8; 100 mmol/l) was used in the delta-ALA-D activity assay instead of potassium phosphate buffer (PB - pH: 6.8; 100 mmol/l). delta-ALA-D inhibition, probably, is mediated by the oxidation of -SH groups caused by the auto-oxidation of AA promoted by metals or another oxidizing system present in liver supernatants. This hypothesis was confirmed by studying dithiothreitol (DTT - 400 micromol/l) oxidation, as a model of enzyme thiols, where we observed that the mechanism underlying DTT and delta-ALA-D oxidation caused by ascorbate is the same. The difference observed between different buffers may be related to the oxidation of Fe(II) to Fe(III) that was more accentuated in PB than in MOPS buffer. The presence of ethilenediamintetraacetic acid (EDTA - 100 micromol/l) and Fe(III) (5 micromol/l) stimulated DTT oxidation more in PB than in MOPS buffer. Deferroxamine (DF - 100 micromol/l) considerably decreased DTT oxidation. Catalase (0.4 mg/ml) and Superoxide dismutase (SOD - 300 U/ml) had only a modest effect on DTT oxidation. The present results suggest that delta-ALA-D inhibition by AA is mediated primarily by the oxidized form of AA and reactive oxygen species play only a modest role in the process. |
| المشرفين على المادة: | 0 (Buffers) E1UOL152H7 (Iron) EC 4.2.1.24 (Porphobilinogen Synthase) PQ6CK8PD0R (Ascorbic Acid) T8ID5YZU6Y (Dithiothreitol) |
| تواريخ الأحداث: | Date Created: 20050805 Date Completed: 20051130 Latest Revision: 20190720 |
| رمز التحديث: | 20221213 |
| DOI: | 10.1248/bpb.28.1485 |
| PMID: | 16079498 |
| قاعدة البيانات: | MEDLINE |
| تدمد: | 0918-6158 |
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| DOI: | 10.1248/bpb.28.1485 |