title: o-quinone/quinone methide isomerase: a novel enzyme preventing the destruction of self-matter by phenoloxidase-generated quinones during immune response in insects.
abstract: Melanization and encapsulation of invading foreign organisms observed during the immune response in insects is known to be due to the action of activated phenoloxidase. Phenoloxidase-generated quinones are deposited either directly or after self-polymerization on foreign objects accounting for the observed reactions. Since the reactions of quinones are nonenzymatic, they do not discriminate self from nonself and hence will also destroy self-matter. In this report we present evidence for the presence of a novel quinone/quinone methide isomerase in the hemolymph of Sarcophaga bullata which destroys long-lived quinones and hence acts to protect the self-matter. Quinone methides, formed by the action of this enzyme on physiologically important quinones, being unstable undergo rapid hydration to form nontoxic metabolites.
authors.affiliation: Department of Biology, University of Massachusetts, Boston 02125.
authors.forename: S J
authors.initials: SJ
authors.lastname: Saul
authors.forename: M
authors.initials: M
authors.lastname: Sugumaran
mesh_terms: D000818:Animals; D004156:Catechol Oxidase / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000031:analogs & derivatives / Q000378:metabolism; D006458:Hemolymph / Q000201:enzymology*; D007313:Insecta / Q000276:immunology* / Q000378:metabolism; D019746:Intramolecular Oxidoreductases; D007535:Isomerases / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D011809:Quinones / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D011809:Quinones; C006374:N-acetyldopamine; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase; D007535:Isomerases; D019746:Intramolecular Oxidoreductases; C057265:quinone methide isomerase; D004298:Dopamine