Purification, characterization and activities of two hemolytic and antibacterial proteins from coelomic fluid of the annelid

The coelomic fluid of the earthworm Eisenia fetida andrei exhibits antibacterial, hemolytic and hemagglutinating activities. These activities are mainly mediated by two proteins, named fetidins, of apparent molecular mass 40 kDa and 45 kDa, respectively. For the first time, the two proteins have been purified to homogeneity from dialysed coelomic fluid by means of anion-exchange chromatography. Three peaks had hemolytic activity. The first fraction was found to correspond to the 40 kDa fetidin, the second to mixed 40 and 45 kDa fetidins, the last one to the 45 kDa fetidin. Both purified proteins still exhibited their hemolytic and antibacterial activities as dialysed coelomic fluid did. In this study, the amino-acid sequence of purified proteins is compared to the amino-acid sequence predicted by cDNA. This cDNA was isolated by screening an expression cDNA library from earthworm total tissues (unpublished data).