o-Quinone/quinone methide isomerase: A novel enzyme preventing the destruction of self-matter by phenoloxidase-generated quinones during immune response in insects

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 o...

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Bibliographic Details
Published in:FEBS letters 1989-06, Vol.249 (2), p.155-158
Main Authors: Saul, Steven J., Sugumaran, Manickam
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Animals
Biological and medical sciences
Catechol Oxidase - metabolism
Chemical Phenomena
Chemistry
Chromatography, High Pressure Liquid
Diptera
Dopamine - analogs & derivatives
Dopamine - metabolism
Enzymes and enzyme inhibitors
Fundamental and applied biological sciences. Psychology
haemolymph
Hemolymph - enzymology
Immunity
Insecta - immunology
Insecta - metabolism
Intramolecular Oxidoreductases
Isomerases
Isomerases - metabolism
Melanization
Monophenol Monooxygenase - metabolism
NADA, N-acetyldopamine
NANE, N-acetyl-norepinephrine
o-quinone/quinone methide isomerase
Phenoloxidase
Quinone methide
Quinone tautomerase
Quinones - metabolism
Sarcophaga bullata
Sarcophagidae
Spectrophotometry, Ultraviolet
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Summary: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.
ISSN:0014-5793
1873-3468
DOI:10.1016/0014-5793(89)80614-3