Zn (II) Protoporphyrin IX is an inhibitor of heme oxygenase (the enzyme that catalyzes the conversion of heme to biliverdin in the heme degradation pathway) and guanylyl cyclase. Heme oxygenase has been implicated in tumor cell resistance to chemotherapy, reduction of free radical formation and inflammation, and associated with vascular repair.h4>StorageZinc (II) Protoporphyrin IX is stable for at least one year when stored as a solid, protected from moisture, at -20 C. Protect from light. This item is non returnable