| Type: | Conserved_site | Name: | Haem oxygenase conserved site |
| Description: | Haem oxygenase () (HO) [] is the microsomal enzyme that, in animals, carries out the oxidation of haem, it cleaves the haem ring at the alpha-methene bridge to form biliverdin and carbon monoxide []. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. In mammals there are three isozymes of haem oxygenase: HO-1 to HO-3. The first two isozymes differ in their tissue expression and their inducibility: HO-1 is highly inducible by its substrate haem and by various non-haem substances, while HO-2 is non-inducible. It has been suggested [] that HO-2 could be implicated in the production of carbon monoxide in the brain where it is said to act as a neurotransmitter. In the genome of the chloroplast of red algae as well as in cyanobacteria, there is a haem oxygenase (gene pbsA) that is the key enzyme in the synthesis of the chromophoric part of the photosynthetic antennae []. A haem oxygenase is also present in the bacteria Corynebacterium diphtheriae(gene hmuO), where it is involved in the acquisition of iron from the host haem []. There is, in the central section of these enzymes, a well-conserved region centred on a histidine residue. | Short Name: | Haem_oxygenase_CS |
