cyclo(L-Pro-L-Trp-L-Val-L-Pro-L-Leu-L-Ile-L-Pro-L-Ile)

carbon monoxide

cyclo[-L-Ile-D-Ile-L-Lys-L-Val-D-Phe-D-Leu-L-Ile-D-Ala-]

cyclo[-L-Val-D-Ile-L-Lys-L-Ile-D-Phe-D-Leu-L-Ile-D-Ala-]