Heme oxygenase is the rate limiting enzyme in the heme degradation pathway. HMOX2, also known as HO-2, belongs to the heme oxygenase family. It can catalyze the oxidative cleavage of heme on the α - methylene bridge carbon, releasing it in the form of carbon monoxide (CO) to produce biliverdin IX α, while releasing the central heme iron chelate as ferrous.
