Nitro-oleic acid, a novel and irreversible inhibitor of xanthine oxidoreductase.
Xanthine oxidoreductase (XOR) generates proinflammatory oxidants and secondary nitrating species, with inhibition of XOR proving beneficial in a variety of disorders. Electrophilic nitrated fatty acid derivatives, such as nitro-oleic acid (OA-NO2), display anti-inflammatory effects with pleiotropic properties. Nitro-oleic acid inhibits XOR activity in a concentration-dependent manner with an IC50 of 0.6 microM, limiting both purine oxidation and formation of superoxide (O2.). Enzyme inhibition by OA-NO2 is not reversed by thiol reagents, including glutathione, beta-mercaptoethanol, and dithiothreitol. Structure-function studies indicate that the carboxylic acid moiety, nitration at the 9 or 10 olefinic carbon, and unsaturation is required for XOR inhibition. Enzyme turnover and competitive reactivation studies reveal inhibition of electron transfer reactions at the molybdenum cofactor accounts for OA-NO2-induced inhibition. Importantly, OA-NO2 more potently inhibits cell-associated XOR-dependent O2. production than does allopurinol. Combined, these data establish a novel role for OA-NO2 in the inhibition of XOR-derived oxidant formation.
Kelley
Eric E
EE
Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA. ekelley@pitt.edu
Batthyany
Carlos I
CI
Hundley
Nicholas J
NJ
Woodcock
Steven R
SR
Bonacci
Gustavo
G
Del Rio
J Mauricio
JM
Schopfer
Francisco J
FJ
Lancaster
Jack R
JR
Freeman
Bruce A
BA
Tarpey
Margaret M
MM
D000818:Animals; D001011:Aorta / Q000166:cytology; D002417:Cattle; D004229:Dithiothreitol / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005227:Fatty Acids / Q000737:chemistry; D005978:Glutathione / Q000378:metabolism; D020128:Inhibitory Concentration 50; D008623:Mercaptoethanol / Q000378:metabolism; D009829:Oleic Acids / Q000378:metabolism*; D010100:Oxygen / Q000737:chemistry; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism; D014968:Xanthine Dehydrogenase / Q000378:metabolism*
C521487:10-nitro-oleic acid; D004791:Enzyme Inhibitors; D005227:Fatty Acids; D009829:Oleic Acids; D013481:Superoxides; D008623:Mercaptoethanol; D014968:Xanthine Dehydrogenase; D005978:Glutathione; D010100:Oxygen; D004229:Dithiothreitol