A metal-free porphyrin, C32H32N4(COOH)2, that combines with iron to form the heme of hemoglobin, myoglobin, cytochrome, and other iron-containing proteins.

• 原卟啉一种不含金属的卟啉，C32H32N4（COOH）2，与铁结合形成血红蛋白、肌红蛋白、细胞色素和其它含铁蛋白质的血红素