Tarantula Hemocyanin Shows Phenoloxidase Activity

Tarantula hemocyanin shows phenoloxidase activity.

An enzyme generally catalyzes one well defined reaction with high specificity and efficiency. We report here in contrast that the copper protein hemocyanin of the tarantula Eurypelma californicum exhibits two different functions. These occur at the same active site. While hemocyanin usually is an oxygen carrier, its function can be transformed totally to monophenoloxidase and o-diphenoloxidase ...

SDS-induced phenoloxidase activity of Helix aspersa maxima hemocyanin

Oxygen-transporting protein of the hemolimph of snails Helix aspersa maxima (HaH) was converted from being an oxygen carrier to a form which exhibited phenoloxidase activity by incubation with sodium dodecyl sulfate (SDS). On treatment with 1.73 mM SDS, for 3 min, significant increase of catalytic efficiency of hemocyanin towards substrate catechol (kcat/Km = 34.56 mM.min -1 versus kcat/Km = 0....

Hemocyanin with phenoloxidase activity in the chitin matrix of the crayfish gastrolith.

Gastroliths are transient extracellular calcium deposits formed by the crayfish Cherax quadricarinatus von Martens on both sides of the stomach wall during pre-molt. Gastroliths are made of a rigid chitinous organic matrix, constructed as sclerotized chitin-protein microfibrils within which calcium carbonate is deposited. Although gastroliths share many characteristics with the exoskeleton, the...

Phenoloxidase activity of hemocyanin in whiteleg shrimp Penaeus vannamei: conversion, characterization of catalytic properties, and role in postmortem melanosis.

Latent phenoloxidase activity of hemocyanin (Hc) in whiteleg shrimp Penaeus vannamei was assayed to determine its potential involvement in postmortem melanosis. Conversion of pure 12-mer, but not 6-mer, hemocyanin to phenoloxidase by endogenous (serine proteinases) and exogenous (SDS) effectors demonstrated the need of complex aggregation for displaying enzyme activity. Because Hc was converted...

Hemocyanin-derived Phenoloxidase; Biochemical and Cellular Investigations of Innate Immunity By