A NOVEL PROTEIN, LYSENIN, THAT CAUSES CONTRACTION OF THE ISOLATED RATAORTA - ITS PURIFICATION FROM THE CELOMIC FLUID OF THE EARTHWORM, EISENIA-FOETIDA

A novel protein that causes contraction of strips of isolated rat aort a and kills rats upon intravenous injection was purified from the coel omic fluid of the earthworm, Eisenia foetida, by the anion-exchange hi gh-performance liquid chromatography and size-exclusion high-performan ce Liquid chromatography. The protein had a molecular weight of 41 kDa , as determined by sodium dodecyl sulfate-polyacrylamide gel electroph oresis. Contraction of rat aorta was induced at concentrations above 1 0(-9)M. Six partial amino acid sequences of the protein revealed the a bsence of any significant homology to those of previously characterize d proteins, suggesting that the protein is a novel biologically active protein. The protein was named lysenin. In addition, another protein with a molecular weight of 42 kDa, whose amino acid sequence resembled that of lysenin, was also isolated, but it had weak contractive activ ity.