Hemolymph phenol oxidases in Drosophila melanogaster, Locusta migratoria, and Austropotamobius pallipes.
The early enzyme-mediated reaction sequence in the biosynthesis of melanin from L-tyrosine involves an initial hydroxylation (monophenol oxidase activity, MPO) of the aromatic amino acid precursor to form L-dopa (3,4-dihydroxyphenylalanine), and the ensuing oxidation (diphenol oxidase activity, DPO) of the resultant diphenol to form dopaquinone. By means of high pressure liquid chromatography with electrochemical detection (HPLC-ED) both phenol oxidase activities were observed in the blood (hemolymph) of two species of insect, third-stage larvae of Drosophila melanogaster and adult Locusta migratoria, and in an adult fresh-water crayfish, Austropotamobius pallipes. These results establish that in each species MPO and DPO can be detected readily without the use of exogenous activators.
Nappi
A J
AJ
Department of Biology, Loyola University of Chicago, IL 60626.
Seymour
J
J
D000818:Animals; D003400:Astacoidea / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D004331:Drosophila melanogaster / Q000201:enzymology*; D004563:Electrochemistry; D006110:Grasshoppers / Q000201:enzymology*; D006458:Hemolymph / Q000201:enzymology*; D007700:Kinetics; D007814:Larva; D014442:Monophenol Monooxygenase / Q000302:isolation & purification / Q000378:metabolism*
D014442:Monophenol Monooxygenase