SMILES: C1=CC=C(C=C1)C[C@@H](C(=O)N[C@@H](CCC[NH+]=C(N)N)C(=O)[O-])[NH3+]
Description: The molecule is a peptide cation obtained by deprotonation of the carboxy terminus and protonation of the side-chain guanidino group and the amino terminus of Phe-Arg; major species at pH 7.3. It is a conjugate acid of a Phe-Arg.