title: Hemocyte components in crustaceans convert hemocyanin into a phenoloxidase-like enzyme.
abstract: The functional conversion of hemocyanin (Hc), an oxygen transporter, into an enzyme was investigated in crustaceans. Hc is converted into a phenoloxidase-like enzyme by hemocyte components, which is triggered by beta-1,3-glucan. This activation is severely hampered with leupeptin and E-64 treatment, indicating that the serine/cysteine proteases in the hemocytes are involved in the activation. In a SDS-PAGE-analysis, no change was observed between normal and activated Hc under reduced conditions. However, under non-reduced condition of normal Hc, several minor bands were observed at oligomeric position of Hc subunit, which disappeared upon activation. These results indicate that a split of the reductive bond, such as the disulfide bond between subunits, is essential for Hc activation. This is the first report to show the enzymatic conversion of Hc and the presence of the covalent bond in the Hc subunit of crustaceans.
authors.affiliation: Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Adachi
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirata
authors.forename: Takaaki
authors.initials: T
authors.lastname: Nishioka
authors.forename: Morihiko
authors.initials: M
authors.lastname: Sakaguchi
mesh_terms: D000818:Animals; D004156:Catechol Oxidase / Q000737:chemistry; D004220:Disulfides; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000737:chemistry; D006433:Hemocyanins / Q000737:chemistry* / Q000378:metabolism*; D006434:Hemocytes / Q000737:chemistry; D014442:Monophenol Monooxygenase / Q000737:chemistry* / Q000378:metabolism; D033561:Penaeidae; D011480:Protease Inhibitors / Q000494:pharmacology
chemical_list: D004220:Disulfides; D004792:Enzyme Precursors; D011480:Protease Inhibitors; D006433:Hemocyanins; C038451:pro-phenoloxidase; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase