Etelcalcetide Impurity 27

Ac-D-Cys (H-Cys-OH) -D-Ala-D-Arg-D-Arg-D-Arg-D-Arg-NH2; S- (((S) -2-acetamido-3- (((R) -1- (((R) -1- (((R) -1- (((R) -1- (((R) -1-amino-5-guanidino-1-oxopentan-2-yl) amino) -5-guanidino-1-oxopentan-2-yl) amino) -5-guanidino-1-oxopentan-2-yl) amino) -5-guanidino-1-oxopentan-2-yl) amino) -1-oxopropan-2-yl) amino) -3-oxopropyl) thio) -L-cysteine