Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.17.3.2 (xanthine oxidase)
 8,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A chemiluminescent substrate reagent for use in a sandwich immunoassay for the model antigen mouse interleukin-5 (IL-5) was developed using xanthine oxidase and luminol. Various parameters involved in this chemiluminescent reaction have been studied, including the substrate hypoxanthine, luminol and the Fe(II)-EDTA complex. Addition of the Fe(II)-EDTA complex enhances the chemiluminescence signal considerably. The xanthine oxidase-catalyzed chemiluminescent immunoassay was compared to horseradish peroxidase-linked immunoassays with luminol as chemiluminescent, and tetramethyl benzidine as colorimetric substrate. The detection limit of the xanthine oxidase-luminol assay was found to be about 0.6 pg/ml IL-5, whereas the peroxidase-catalyzed immunoassays have detection limits of about 1.3 (HRP-TMB) and 2.9 pg/ml (HRP-luminol) IL-5.
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PMID:Application of xanthine oxidase-catalyzed luminol chemiluminescence in a mouse interleukin-5 immunoassay. 889 Sep 3

Eosinophils and increased production of nitric oxide (NO) and superoxide, components of peroxynitrite, have been implicated in the pathogenesis of a number of allergic disorders including asthma. Peroxynitrite induced protein nitration may compromise enzyme and protein function. We hypothesized that peroxynitrite may modulate eosinophil migration by modulating chemotactic cytokines. To test this hypothesis, the eosinophil chemotactic responses of regulated on activation, normal T cell expressed and secreted (RANTES) and interleukin (IL)-5 incubated with and without peroxynitrite were evaluated. Peroxynitrite-attenuated RANTES and IL-5 induced eosinophil chemotactic activity (ECA) in a dose-dependent manner (P < 0.05) but did not attenuate leukotriene B4 or complement-activated serum ECA. The reducing agents deferoxamine and dithiothreitol reversed the ECA inhibition by peroxynitrite, and exogenous L-tyrosine abrogated the inhibition by peroxynitrite. PAPA-NONOate, a NO donor, or superoxide generated by lumazine or xanthine and xanthine oxidase, did not show an inhibitory effect on ECA. The peroxynitrite generator, 3-morpholinosydnonimine, caused a concentration-dependent inhibition of ECA. Peroxynitrite reduced RANTES and IL-5 binding to eosinophils and resulted in nitrotyrosine formation. These findings are consistent with nitration of tyrosine by peroxynitrite with subsequent inhibition of RANTES and IL-5 binding to eosinophils and suggest that peroxynitrite may play a role in regulation of eosinophil chemotaxis.
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PMID:Effects of reactive oxygen and nitrogen metabolites on RANTES- and IL-5-induced eosinophil chemotactic activity in vitro. 1043 51