Endothelin-1 (ET-1), a peptide of 21 amino acid residues, is the most potent vasoconstrictive substance known. Originally isolated from porcine aortic endothelial cells, ET-1 is now known to be one of a family of three mammalian vasoactive peptides that also includes Endothelin-2 (ET-2) and Endothelin-3 (ET-3). These related peptides differ from ET-1 at two and six amino acid residue positions, respectively. A fourth peptide, vasoactive intestinal contractor (VIC), is sometimes classified as rat ET-2. All members of the endothelin family contain two essential disulfide bridges and six conserved amino acid residues at the C-terminus. Additionally, all of the endothelin family members are synthesized initially as prepropolypeptides of approximately 200 amino acid residues encoded by separate genes. These are proteolytically cleaved to produce biologically-inactive propolypeptides of approximately 40 amino acid residues termed “big endothelins”. Big ET-1 is cleaved by the proteolytic action of a membrane-bound metalloprotease [endothelin-converting enzyme (ECE-1)] producing the 21 amino acid residue active peptide. The biochemistry and biology of the endothelins have been the subject of several reviews.
Storage: Store at -20 °C for one year. Avoid repeated freeze/thaw cycles.