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

Certain products of arachidonic acid have been demonstrated recently to possess chemotactic activity for human polymorphonuclear leukocytes (PMN). Enzymatic (lipoxygenase, cyclooxygenase) generation of these lipid chemotaxins proceeds through the formation of intermediate lipid peroxides. Since lipid peroxidation can be mediated by oxygen-derived free radicals, we have examined whether chemotactically active products of arachidonic acid could be produced by exposing this unsaturated fatty acid to a superoxide-generating system. A lipid with potent chemotactic activity for human PMN was produced by incubating arachidonic acid with xanthine oxidase and acetaldehyde. Generation of chemotactic activity was time-dependent and could be inhibited to the greatest extent by scavengers of singlet oxygen (i.e., histidine, uric acid, and 2,5-dimethylfuran). Inhibition was also observed with scavengers of superoxide anion radicals (i.e., superoxide dismutase), hydrogen peroxide (i.e., catalase), and hydroxyl radicals (i.e., mannitol). Silica gel thin-layer radiochromatography demonstrated a single peak with chemotactic activity (Rf = 0.33-0.38) distinct from unaltered arachidonic acid. The product of arachidonic acid was chemotactic at a concentration of 3.0 ng/ml and chemokinetic at concentrations of 0.75-1.5 ng/ml. Since PMN produce oxygen-derived free radicals and singlet oxygen upon stimulation of their plasma membrane, and since arachidonic acid is widely distributed in human tissues, free radical-mediated generations of chemotactic activity from arachidonic acid may play an important role in amplifying inflammatory responses.
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PMID:Generation of a chemotactic lipid from a arachidonic acid by exposure to a superoxide-generating system. 625 92

A biologically active lipid was produced by incubating arachidonic acid with a superoxide-generating system consisting of xanthine oxidase plus acetaldehyde. The lipid proved to be a potent chemoattractant for human polymorphonuclear leukocytes and also was capable of inhibiting platelet aggregation induced either by arachidonic acid or by the endoperoxide analog, 9,11-azoprostanoid III. Generation of the biologically active lipid required the presence of all of the reactants, was time-dependent and could be inhibited by scavengers of superoxide, hydroxyl radicals, and singlet oxygen. Silica gel thin-layer radiochromatography demonstrated a single peak with biological activity, distinct from unaltered arachidonic acid. The biologically active lipid was most likely generated by the peroxidation of arachidonic acid. Biologically active products of arachidonic acid formed nonenzymatically by the action of oxygen-derived free radicals may play important roles in the mediation and modulation of inflammatory responses.
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PMID:Generation of a biologically active lipid from arachidonic acid by exposure to a superoxide-generating system. 694 72