Reduction of organic nitrates catalysed by xanthine oxidoreductase under anaerobic conditions

Xanthine oxidoreductase catalyses the anaerobic reduction of glyceryl trinitrate (GTN), isosorbide dinitrate and isosorbide mononitrate to inorganic nitrite using xanthine or NADH as reducing substrates. Reduction rates are much faster with xanthine as reducing substrate than with NADH. In the prese...

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Bibliographic Details
Published inBiochimica et biophysica acta Vol. 1527; no. 1; pp. 81 - 87
Main Authors Doel, Justin J, Godber, Ben L.J, Eisenthal, Robert, Harrison, Roger
Format Journal Article
LanguageEnglish
Published Netherlands Elsevier B.V 02.07.2001
Subjects
Anaerobiosis - physiology
Animals
Catalysis
Cattle
Flavin-Adenine Dinucleotide - metabolism
Glyceryl trinitrate
Molybdenum - metabolism
Nitrates - metabolism
Nitric oxide
Nitrites - analysis
Oxidation-Reduction
Xanthine - metabolism
Xanthine dehydrogenase
Xanthine Dehydrogenase - metabolism
Xanthine oxidase
Xanthine Oxidase - metabolism
IS-2-MN, isosorbide 2-mononitrate
Glyceryl trinitrate
XDH, xanthine dehydrogenase
Xanthine dehydrogenase
XO, xanthine oxidase
IS-5-MN, isosorbide 5-mononitrate
AFR, activity to flavin ratio
XOR, xanthine oxidoreductase
Nitric oxide
GTN, glyceryl trinitrate
Bicine, N, N-bis(2-hydroxyethyl)glycine
ISDN, isosorbide dinitrate
IDP, iodonium diphenyl
Xanthine oxidase
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Summary:Xanthine oxidoreductase catalyses the anaerobic reduction of glyceryl trinitrate (GTN), isosorbide dinitrate and isosorbide mononitrate to inorganic nitrite using xanthine or NADH as reducing substrates. Reduction rates are much faster with xanthine as reducing substrate than with NADH. In the presence of xanthine, urate is produced in essentially 1:1 stoichiometric ratio with inorganic nitrite, further reduction of which is relatively slow. Organic nitrates were shown to interact with the FAD site of the enzyme. In the course of reduction of GTN, xanthine oxidoreductase was progressively inactivated by conversion to its desulpho form. It is proposed that xanthine oxidoreductase is one of several flavoenzymes that catalyse the conversion of organic nitrate to inorganic nitrite in vivo. Evidence for its further involvement in reduction of the resulting nitrite to nitric oxide is discussed.
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ISSN:0304-4165
0006-3002
1872-8006
DOI:10.1016/S0304-4165(01)00148-9