Isolation and characterization of porcine endothelin-like peptide

Two endogenous molecules possessing an endothelin-like sequence with an apparent molecular weight of 7 kDa were isolated from serum-free culture medium of porcine aortic endothelial cells, using a specific radioimmunoassay. N-terminal sequences of two molecules were identical to each other and were Ser-Leu-Lys-Asp-Leu-Phe-Pro-Ala-Lys-Ala-Ala-Asp-Arg-Arg-Asp-Arg-X-Gln-X- Ala-X- Gln-Lys-Asp, which corresponds to the sequence [94-117] of preproendothelin-1. This finding indicates that these two molecules may be closely related peptides such as the oxidized form or disulfide analogues and also suggests that the endogenous peptide possessing an endothelin-like sequence is generated by proteolytic cleavage at paired basic amino acids Arg92-Arg93. Further studies on the structure and function of new endogenous peptides possessing an endothelin-like sequence are ongoing in our laboratory.