Definition: Porphyrins with four methyl, two vinyl, and two propionic acid side chains attached to the pyrrole rings. Protoporphyrin IX occurs in hemoglobin, myoglobin, and most of the cytochromes.
protoporphyrin IX [ PPIX,protoporphyrin IX dihydride,protoporphyrin IX, disodium salt ] RN given refers to parent cpd; structure in Merck Index, 9th ed, #7685