title: An oxygen transporter hemocyanin can act on the late pathway of melanin synthesis.
abstract: 5,6-Dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) are precursors of eumelanin. The effects of crustacean hemolymph proteins on these eumelanin-related metabolites were investigated. Zymogram analysis indicated that polymers of hemocyanin (Hc) subunits converted DHI into black pigment while no effects were observed using DHICA as a substrate. Spectrum changes for mixtures of purified Hc and DHI showed a profile similar to oxidized DHI by mushroom tyrosinase while Hc had only slight effects on DHICA. Typical inhibitors of tyrosinase and phenoloxidase severely hampered the production of oxidized DHI. Taken together with previous results, these data indicate that Hc plays a crucial role in the conversion of DHI in the hemolymph of crustaceans, which promotes late reactions in the melanin synthetic pathway as well as early reactions (oxidation of tyrosine and DOPA to dopaquinone).
authors.affiliation: Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Japan.
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Adachi
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Wakamatsu
authors.forename: Shosuke
authors.initials: S
authors.lastname: Ito
authors.forename: Nari
authors.initials: N
authors.lastname: Miyamoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kokubo
authors.forename: Takaaki
authors.initials: T
authors.lastname: Nishioka
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirata
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006433:Hemocyanins / Q000737:chemistry / Q000378:metabolism*; D006458:Hemolymph / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007211:Indoles / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D008543:Melanins / Q000096:biosynthesis* / Q000378:metabolism; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors; D010100:Oxygen / Q000378:metabolism*; D033561:Penaeidae; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D007211:Indoles; D008543:Melanins; C030692:5,6-dihydroxy-2-indolylcarboxylic acid; D006433:Hemocyanins; D014442:Monophenol Monooxygenase; D010100:Oxygen; C033871:5,6-dihydroxyindole