The molecule is the conjugate acid of oxidized Cypridina luciferin arising from selective protonation of the guanidino group; major species at pH 7.3. It is a conjugate acid of an oxidized Cypridina luciferin.
diaminomethylidene-[3-[6-(1H-indol-3-yl)-3-[[(2S)-2-methylbutanoyl]amino]pyrazin-2-yl]propyl]azanium