Latent phenoloxidase activity and N-terminal amino acid sequence of hemocyanin from Bathynomus giganteus, a primitive crustacean.
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.
Pless
Dorothy D
DD
Instituto de Neurobiologi;a, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, 76230, Querétaro, Qro., Mexico. pless@calli.cnb.unam.mx
Aguilar
Manuel B
MB
Falcón
Andrés
A
Lozano-Alvarez
Enrique
E
Heimer de la Cotera
Edgar P
EP
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002850:Chromatography, Gel; D017124:Conserved Sequence; D003445:Crustacea; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D006433:Hemocyanins / Q000737:chemistry* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D021122:Protein Subunits; D016415:Sequence Alignment; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013379:Substrate Specificity; D013501:Surface-Active Agents / Q000494:pharmacology
D021122:Protein Subunits; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D006433:Hemocyanins; D014442:Monophenol Monooxygenase