Latent phenoloxidase activity and N-terminal amino acid sequence of hemocyanin from Bathynomus giganteus, a primitive crustacean.
Arch Biochem Biophys
; 409(2): 402-10, 2003 Jan 15.
Article
em En
| MEDLINE
| ID: mdl-12504908
ABSTRACT
N-terminal amino acid sequences for the two hemocyanin subunits from the deep-sea crustacean Bathynomus giganteus have been determined by Edman degradation, providing the first sequence information for a hemocyanin from an isopod. In addition, purified hemocyanin from B. giganteus exhibited phenoloxidase activity in the presence of sodium dodecyl sulfate. Although a natural activator has not yet been identified, a preliminary study of the enzyme indicated a K(m) of 5mM for dopamine and an initial rate of 0.1 micromol per min per mg protein, values consistent with a significant role for this enzyme in the innate immune system of B. giganteus. Moreover, after separation of hemolymph by alkaline polyacrylamide gel electrophoresis, the only detectable phenoloxidase activity coincided with the two hemocyanin subunits. The hemocyanin of this primitive crustacean may fulfill dual functions, both as oxygen carrier and as the phenoloxidase crucial for host defense.
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Base de dados:
MEDLINE
Assunto principal:
Hemocianinas
/
Monofenol Mono-Oxigenase
/
Crustáceos
Idioma:
En
Ano de publicação:
2003
Tipo de documento:
Article