title: Dual effect of nitric oxide on phenoloxidase-mediated melanization.
abstract: The study has demonstrated a dual effect of nitric oxide on phenoloxidase (PO)-mediated DOPA oxidation and melanization process. NO generated at low rates proportionally increased in PO-mediated DOPA oxidation. Competitive PO inhibitor, phenylthiourea, resulted in significant inhibition of NO-mediated DOPA oxidation. Further analysis using fluorescent and EPR methods demonstrated that the effect of NO on DOPA oxidation is explained by oxidation of NO to NO2 at the active site of PO followed by oxidation of DOPA by NO2. On the contrary, the bolus addition of NO gas solution resulted in a significant decrease in observed PO activity. Similar dose-dependent effect of NO was observed for the insect's haemocytes quantified as percentage of melanized cells after treatment with nitric oxide. In conclusion, the results of the study suggest that NO may have a significant regulatory role on melanization process in invertebrates as well as in human and result in protective or damaging effects.
authors.affiliation: a Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences , Novosibirsk , Russia and.
authors.forename: Urikhan
authors.initials: U
authors.lastname: Sanzhaeva
authors.affiliation: b Institute of Systematics and Ecology of Animals, Siberian Branch of the Russian Academy of Sciences , Novosibirsk , Russia.
authors.forename: Yana
authors.initials: Y
authors.lastname: Vorontsova
authors.affiliation: a Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences , Novosibirsk , Russia and.
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Glazachev
authors.affiliation: a Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences , Novosibirsk , Russia and.
authors.forename: Irina
authors.initials: I
authors.lastname: Slepneva
mesh_terms: D008543:Melanins / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D009569:Nitric Oxide / Q000494:pharmacology*
chemical_list: D008543:Melanins; D009569:Nitric Oxide; D014442:Monophenol Monooxygenase
keywords: Melanization; nitric oxide; phenoloxidase