Oxygenase

An oxygenase is any enzyme that oxidizes a substrate by transferring the oxygen from molecular oxygen O₂ (as in air) to it. The oxygenases form a class of oxidoreductases; their EC number is EC 1.13 or EC 1.14.

Discoverers

Oxygenases were discovered in 1955 simultaneously by two groups, Osamu Hayaishi from Japan^[1][2][3] and Howard S. Mason from the US.^[4][5] Hayaishi was awarded the 1986 Wolf Prize in Medicine "for the discovery of the oxygenase enzymes and elucidation of their structure and biological importance."^[6]

Chemical Makeup

Oxygenases consist of both constitutive and inducible isozymes (HO-1, HO-2). These constitute a major intracellular source of iron and carbon monoxide^[7]

Types

There are two types of oxygenases:

• Monooxygenases, or mixed function oxidase, transfer one oxygen atom to the substrate, and reduce the other oxygen atom to water.
• Dioxygenases, or oxygen transferases, incorporate both atoms of molecular oxygen (O₂) into the product(s) of the reaction.^[8]

Among the most important monooxygenases are the cytochrome P450 oxidases, responsible for breaking down numerous chemicals in the body.

References

1. ↑ Hayaishi et al. (1955) Mechanism of the pyrocatechase reaction, J. Am. Chem. Soc. 77 (1955) 5450-5451
2. ↑ Sligar SG, Makris TM, Denisov IG (2005). "Thirty years of microbial P450 monooxygenase research: peroxo-heme intermediates--the central bus station in heme oxygenase catalysis". Biochem. Biophys. Res. Commun. 338 (1): 346–54. doi:10.1016/j.bbrc.2005.08.094. PMID 16139790. 
3. ↑ Hayaishi O (2005). "An odyssey with oxygen". Biochem. Biophys. Res. Commun. 338 (1): 2–6. doi:10.1016/j.bbrc.2005.09.019. PMID 16185652. 
4. ↑ Mason HS, Fowlks WK, and Peterson E. (1955) Oxygen transfer and electron transport by the phenolase complex. J. Am. Chem. Soc.; 77(10) pp 2914 - 2915
5. ↑ Waterman MR (2005). "Professor Howard Mason and oxygen activation". Biochem. Biophys. Res. Commun. 338 (1): 7–11. doi:10.1016/j.bbrc.2005.08.120. PMID 16153596. 
6. ↑ "The Medicine Prize Committee unanimously decided that the Wolf Prize in Medicine for 1986 be awarded to Osamu Hayaishi". Wolf Foundation. Retrieved May 12, 2014. 
7. ↑ SW, Ryter; J, Alam (April 2006). "Heme oxygenase-1/carbon monoxide: from basic science to therapeutic applications.". Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, The University of Pittsburgh School of Medicine. PMID 16601269. 
8. ↑ Bugg TDH (2003). "Dioxygenase enzymes: catalytic mechanisms and chemical models". Tetrahedron. 59 (36): 7075–7101. doi:10.1016/S0040-4020(03)00944-X.