DOPACHROME CONVERSION ACTIVITY IN AEDES-AEGYPTI - SIGNIFICANCE DURINGMELANOTIC ENCAPSULATION OF PARASITES AND CUTICULAR TANNING

Phenol oxidase (PO) and dopachrome conversion enzyme (DCE) were partia lly purified from Aedes aegypti larvae by ammonium sulfate fractionati on. PO from A. aegypti functions in the hydroxylation of monophenols ( e.g., tyrosine and tyramine) to their related o-diphenols, and the oxi dation of o-diphenols (e.g., L-dopa, dopamine, N-acetyldopamine) to th eir respective o-quinones. Partially purified DCE showed high specific ity toward dopachrome generated from dopa with the L-configuration. Th e combined effects of PO and DCE significantly accelerated melanizatio n pathways when L-dopa was used as substrate. Significant DCE activity also was detected in hemolymph samples from adult, female A. aegypti, and undoubtedly plays a role in melanotic encapsulation reactions.