The molecule is a dicarboxylic acid dianion obtained by deprotonation of the carboxy groups of (3E)-phycocyanobilin; major species at pH 7.3. It is a dicarboxylic acid dianion and a linear tetrapyrrole anion. It is a conjugate base of a (3E)-phycocyanobilin.
3-[(2Z,5Z)-2-[[3-(2-carboxylatoethyl)-5-[(Z)-[(3E,4R)-3-ethylidene-4-methyl-5-oxopyrrolidin-2-ylidene]methyl]-4-methyl-1H-pyrrol-2-yl]methylidene]-5-[(4-ethyl-3-methyl-5-oxopyrrol-2-yl)methylidene]-4-methylpyrrol-3-yl]propanoate