The molecule is a thirteen-membered polypeptide consisting of p-Glu, Arg, Pro, Arg, Leu, Ser, His, Lys, Gly, Pro, Met, Pro and Phe residues joined in sequence. It has a role as an apoptosis inhibitor, a neuroprotective agent and a human metabolite. It is a tautomer of a [Pyr1]apelin-13(2+).
(2S)-2-[[(2S)-1-[(2S)-2-[[(2S)-1-[2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-(diaminomethylideneamino)-2-[[(2S)-1-[(2S)-5-(diaminomethylideneamino)-2-[[(2S)-5-oxopyrrolidine-2-carbonyl]amino]pentanoyl]pyrrolidine-2-carbonyl]amino]pentanoyl]amino]-4-methylpentanoyl]amino]-3-hydroxypropanoyl]amino]-3-(1H-imidazol-5-yl)propanoyl]amino]hexanoyl]amino]acetyl]pyrrolidine-2-carbonyl]amino]-4-methylsulfanylbutanoyl]pyrrolidine-2-carbonyl]amino]-3-phenylpropanoic acid