The molecule is an iminium betaine resulting from a transfer of two protons from the carboxy groups to the imino groups of anaerobilin; major species at pH 7.3. It is a tautomer of an anaerobilin.
3-[(2Z,5Z)-5-[[2,4-bis(ethenyl)-3-methyl-2H-pyrrol-1-ium-5-yl]methylidene]-2-[[3-(2-carboxylatoethyl)-5-[(Z)-(4-ethenyl-3-methylpyrrol-1-ium-2-ylidene)methyl]-4-methyl-1H-pyrrol-2-yl]methylidene]-4-methylpyrrol-3-yl]propanoate