The ring is the amino-acid sequence, one arc per amino acid, starting at the top and continuing clockwise. Colors match the sequence beads: special, negative, positive, and hydrophobic. A gap means the chain is linear. The outer halo is the compound family. BPC-157 has no end modifications or bound metal, so none are drawn.
BPC-157 is a chain of 15 amino acids from a much larger peptide that a Zagreb team reported in stomach juice in 1993.
Sikirić P, Petek M, Rucman R, et al. A new gastric juice peptide, BPC. An overview of the stomach-stress-organoprotection hypothesis and beneficial effects of BPC. J Physiol Paris. 1993;87:313–327. https://doi.org/10.1016/0928-4257(93)90038-u (PMID 8298609)