The molecule is a peptide cation obtained from the protonation of the N-terminus amino group and L-arginyl side chains, and deprotonation of the C-terminus carboxy group of apelin-12. It is the major species at pH 7.3. It is a conjugate acid of an apelin-12.
(2S)-1-[(2S)-2-[[(2S)-1-[2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-1-[(2S)-2-[[(2S)-5-amino-2-azaniumyl-5-oxopentanoyl]amino]-5-(diaminomethylideneazaniumyl)pentanoyl]pyrrolidine-2-carbonyl]amino]-5-(diaminomethylideneazaniumyl)pentanoyl]amino]-4-methylpentanoyl]amino]-3-hydroxypropanoyl]amino]-3-(1H-imidazol-5-yl)propanoyl]amino]-6-azaniumylhexanoyl]amino]acetyl]pyrrolidine-2-carbonyl]amino]-4-methylsulfanylbutanoyl]pyrrolidine-2-carboxylate