Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Coenzyme Q (CoQ0) and other quinones were shown to be potent insulin secretagogues in the isolated pancreatic islet. The order of potency was CoQ0 congruent to benzoquinone congruent to hydroquinone-menadione. CoQ6 and CoQ10 (ubiquinone), duroquinone and durohydroquinone did not stimulate insulin release. CoQ0's insulinotropism was enhanced in calcium-free medium and CoQ0 appeared to stimulate only the second phase of insulin release. CoQ0 inhibited inositol mono-, bis- and trisphosphate formation. Inhibitors of mitochondrial respiration (rotenone, antimycin A, FCCP and cyanide) and the calcium channel blocker verapamil, did not inhibit CoQ0-induced insulin release. Dicumarol, an inhibitor of quinone reductase, did not inhibit CoQ0-induced insulin release, but it did inhibit glucose-induced insulin release suggesting that the enzyme and quinones play a role in glucose-induced insulin release. Quinones may stimulate insulin release by mimicking physiologically-occurring quinones, such as CoQ10, by acting on the plasma membrane or in the cytosol. Exogenous quinones may bypass the quinone reductase reaction, as well as many reactions important for exocytosis.
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PMID:Stimulation of insulin release from pancreatic islets by quinones. 172 Mar 33

A water-soluble quinone, coenzyme Q0 (CoQ0), was shown to stimulate insulin release, and dicumarol, an inhibitor of quinone reductase, inhibited glucose-induced insulin release in pancreatic islets. Since this suggested that quinone reductase might play some role in physiological insulin release, this enzyme was characterized in islets. More than 90% of the total activity was located in the cytosol, but the specific enzyme activity was highest in the microsomal fraction. The relative rates of activity with various substrates (CoQ0 approximately equal to durohydroquinone greater than menadione greater than duroquinone greater than CoQ6 = CoQ10 greater than ferricyanide) were similar to those described previously for quinone reductase from liver Dicumarol, chlorpromazine, and T3 were much more potent inhibitors of the enzyme when NADPH was the coenzyme than when NADH was the coenzyme. Dicumarol was the most potent inhibitor. The enzyme was not inhibited by rotenone. Islets ranked second to liver in quinone reductase activity, but the activity in islets was much closer to that found in all other tissues examined. Quinone reductase may play a role in insulin secretion.
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PMID:Quinone reductase enzyme activity in pancreatic islets. 187 76