Heme oxygenase 2 is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that in humans is encoded by the HMOX2 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Function

Heme oxygenase

Heme oxygenase

This reaction can occur in virtually every cell; the classic example is the formation of a bruise, which goes through different colors as it gradually heals: red heme to green biliverdin to yellow bilirubin...

, an essential enzyme in heme

Heme

A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...

 catabolism, cleaves heme to form biliverdin

Biliverdin

Biliverdin is a green tetrapyrrolic bile pigment, and is a product of heme catabolism. It is the pigment responsible for a greenish color sometimes seen in bruises.- Metabolism :...

, which is subsequently converted to bilirubin by biliverdin reductase

Biliverdin reductase

Biliverdin reductase is an enzyme found in the liver that facilitates the conversion of biliverdin to bilirubin. It accomplishes this through the reduction of a double-bond between the second and third pyrrole ring into a single-bond....

, and carbon monoxide

Carbon monoxide

Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

, a putative neurotransmitter. Heme oxygenase activity is induced by its substrate heme and by various nonheme substances. Heme oxygenase occurs as 2 isozyme

Isozyme

Isozymes are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. These enzymes usually display different kinetic parameters Isozymes (also known as isoenzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. These enzymes...

s, an inducible heme oxygenase-1 and a constitutive heme oxygenase-2. HMOX1

HMOX1

HMOX1 is a human gene that encodes for the enzyme heme oxygenase 1 . Heme oxygenase is an essential enzyme in heme catabolism, it cleaves heme to form biliverdin....

and HMOX2 (this enzyme) belong to the heme oxygenase family.

Further reading