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Inhibition of NADH-methemoglobin reductase by organic phosphates.
- Source :
-
Biochimica et biophysica acta [Biochim Biophys Acta] 1979 Nov 09; Vol. 571 (1), pp. 112-9. - Publication Year :
- 1979
-
Abstract
- The organic phosphate allosteric effectors of hemoglobin, inositol hexaphosphate, 2,3-diphosphoglycerate, and ATP, interact with NADH-methemoglobin reductase (NADH-diaphorase). Significant inhibitory effects on the enzyme were found when dichlorophenolindophenol, or ferricyanide were used as electron acceptors in place of methemoglobin. In contrast, apparent stimulation of enzyme activity was observed when adult human methemoglobin was used as the electroganic phosphate on the rate of reaction due to its interaction with the substrate methemoglobin to produce the favored T type of quaternary conformation. The inhibitory effect of inositol hexaphosphate on the enzyme is associated with a perturbation in the reactivity of essential sulfhydryl group(s) on the enzyme. It is suggested that the interaction of the organic phosphate with the enzyme as well as with the substrate is significant in determining the overall rate of methemoglobin reduction.
- Subjects :
- 2,6-Dichloroindophenol metabolism
Ferricyanides metabolism
Humans
Inositol Phosphates pharmacology
Methemoglobin metabolism
Sulfhydryl Reagents pharmacology
Cytochrome-B(5) Reductase antagonists & inhibitors
NADH, NADPH Oxidoreductases antagonists & inhibitors
Organophosphorus Compounds pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0006-3002
- Volume :
- 571
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Biochimica et biophysica acta
- Publication Type :
- Academic Journal
- Accession number :
- 497234
- Full Text :
- https://doi.org/10.1016/0005-2744(79)90231-6