Evidence for proteins involved in prophenoloxidase cascade Eisenia fetida earthworms.

The prophenoloxidase cascade represents one of the most important defense mechanisms in many invertebrates. Following the recognition of microbial saccharides by pattern recognition molecules, proteinases cleave inactive prophenoloxidase to its active form, phenoloxidase. Phenoloxidase is a key enzyme responsible for the catalysis of the melanization reaction. Final product melanin is involved in wound healing and immune responses. Prophenoloxidase cascade has been widely described in arthropods; data in other invertebrate groups are less frequent. Here we show detectable phenoloxidase activity in 90-kDa fraction of the coelomic fluid of earthworms Eisenia fetida. Amino acid sequencing of peptides from the active fraction revealed a partial homology with invertebrate phenoloxidases and hemocyanins. Moreover, the level of phenoloxidase activity is lower and the activation slower as compared to other invertebrates.