Plecanatide ASN-ASP-GLU-CYS-GLU-LEU-CYS-VAL-ASN-VAL-ALA-CYS-THR-GLY-CYS-LEU(DISULFIDE BOND CYS1&CYS3,CYS2&CYS4) Plecanatide Impurtiy L-Leucine, L-asparaginyl-L-α-aspartyl-L-α-glutamyl-L-cysteinyl-L-α-glutamyl-L-leucyl-L-cysteinyl-L-valyl-L-asparaginyl-L-valyl-L-alanyl-L-cysteinyl-L-threonylglycyl-L-cysteinyl-, cyclic (4→12),(7→15)-bis(disulfide) Plecanatide impurity Plecanatide USP/EP/BP Prikanatide ATCH(1-39)