Li J
Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison 53706.
Comp Biochem Physiol A Physiol. 1994 Dec;109(4):835-43. doi: 10.1016/0300-9629(94)90231-3.
The biochemical pathway of egg chorion tanning in the mosquito, Aedes aegypti, is described and compared with chorion protein crosslinking in Drosophila and silkmoths and the biochemical pathways of cuticular tanning in insects. Phenol oxidase, dopa decarboxylase and tyrosine are critical components involved in egg chorion tanning in A. aegypti. Tanning of the mosquito egg chorion is initiated following activation of phenol oxidase, which then catalyzes the hydroxylation of tyrosine to dopa and further oxidizes dopa and dopamine to their respective o-quinones. Because intramolecular cyclization is much slower in dopaminequinone than dopaquinone, the chance to react with external nucleophiles to participate in protein crosslinking reactions also is much greater in dopaminequinone than dopaquinone. This might partly explain the necessity for the involvement of dopa decarboxylase in mosquito chorion tanning. Intramolecular cyclization of dopaquinone and dopaminequinone to form dopachrome and dopaminechrome, respectively, the structural rearrangement of these aminochromes to produce 5,6-dihydroxyindole, and the subsequent oxidation of 5,6-dihydroxyindole by phenol oxidase also lead to melanin formation during egg chorion tanning.
描述了埃及伊蚊卵壳鞣化的生化途径，并将其与果蝇和家蚕的卵壳蛋白交联以及昆虫表皮鞣化的生化途径进行了比较。酚氧化酶、多巴脱羧酶和酪氨酸是埃及伊蚊卵壳鞣化过程中的关键成分。蚊子卵壳的鞣化在酚氧化酶激活后开始，酚氧化酶随后催化酪氨酸羟基化为多巴，并进一步将多巴和多巴胺氧化为各自的邻醌。由于多巴胺醌的分子内环化比多巴醌慢得多，多巴胺醌与外部亲核试剂反应参与蛋白质交联反应的机会也比多巴醌大得多。这可能部分解释了多巴脱羧酶参与蚊子卵壳鞣化的必要性。多巴醌和多巴胺醌分别分子内环化形成多巴色素和多巴胺色素，这些氨基色素的结构重排产生5,6-二羟基吲哚，以及随后酚氧化酶对5,6-二羟基吲哚的氧化，也导致卵壳鞣化过程中黑色素的形成。
