Linaclotide Impurity 43

((2S,5R,8S,14R,19R,22S,25S,28R,32R,37R,40S,42aS) -40- (2-amino-2-oxoethyl) -25- (2-carboxyethyl) -22- (4-hydroxybenzyl) -8- ((R) -1-hydroxyethyl) -2-methyl-3,6,9,12,21,24,29,31,38,41,42,48-dodecaoxo-32- ((3,4,5,6-tetrahydroxy-2-oxohexyl) amino) tetracontahydro-1H,36H-37,19- (epiminomethano) -5,28- (methanodithiomethano) pyrrolo[2,1-b1][1,2,19,20]tetrathia[5,8,11,12,15,24,29,30,33,36,39,42]dodecaazacyclotetratetracontine-14-carbonyl) -L-tyrosine