Bilirubin oxidase explained

bilirubin oxidase
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Cas Number:	80619-01-8
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In enzymology, a bilirubin oxidase, BOD or BOx, is an enzyme encoded by a gene in various organisms that catalyzes the chemical reaction

2 bilirubin + O₂

\rightleftharpoons 2 biliverdin + 2 H₂O

This enzyme belongs to the family of oxidoreductases, to be specific those acting on the CH-CH group of donor with oxygen as acceptor. The systematic name of this enzyme class is bilirubin:oxygen oxidoreductase. This enzyme is also called bilirubin oxidase M-1. This enzyme participates in porphyrin and chlorophyll metabolism. It is widely studied as a catalyst for oxygen reduction.^[1]

Two structures of bilirubin oxidase from the ascomycete Myrothecium verrucaria have been deposited in the Protein Data Bank (accession codes and).^{[2] [3]}

The active site consists of four copper centers, reminiscent of laccase. These centers are classified as type I (cys, met, his, his), type II (3his), and two type III (2his).^[4] The latter two centers are arranged in a trinuclear copper cluster forming the active site for oxygen reduction.^[5] The type I copper center is the primary electron acceptor and the site for the reduction of bilirubin.

Further reading

• Murao S, Tanaka N . 1981 . A new enzyme bilirubin oxidase produced by Myrothecium verrucaria MT-1 . Agricultural and Biological Chemistry. 45 . 10 . 2383 - 2384 . 10.1271/bbb1961.45.2383. free .
• Tanaka N, Murao S . 1985 . Reaction of bilirubin oxidase produced by Myrothecium verrucaria MT-1 . Agricultural and Biological Chemistry. 49 . 3 . 843 - 844 . 10.1271/bbb1961.49.843. free .

Notes and References

1. Mano N, Edembe L . Bilirubin oxidases in bioelectrochemistry: features and recent findings . Biosensors & Bioelectronics . 50 . 478–485 . December 2013 . 23911663 . 10.1016/j.bios.2013.07.014 .
2. Mizutani K, Toyoda M, Sagara K, Takahashi N, Sato A, Kamitaka Y, Tsujimura S, Nakanishi Y, Sugiura T, Yamaguchi S, Kano K, Mikami B . 6 . X-ray analysis of bilirubin oxidase from Myrothecium verrucaria at 2.3 A resolution using a twinned crystal . Acta Crystallographica. Section F, Structural Biology and Crystallization Communications . 66 . Pt 7 . 765–770 . July 2010 . 20606269 . 2898457 . 10.1107/S1744309110018828 .
3. Cracknell JA, McNamara TP, Lowe ED, Blanford CF . Bilirubin oxidase from Myrothecium verrucaria: X-ray determination of the complete crystal structure and a rational surface modification for enhanced electrocatalytic O2 reduction . Dalton Transactions . 40 . 25 . 6668–6675 . July 2011 . 21544308 . 10.1039/c0dt01403f .
4. Jones SM, Solomon EI . Electron transfer and reaction mechanism of laccases . Cellular and Molecular Life Sciences . 72 . 5 . 869–883 . March 2015 . 25572295 . 4323859 . 10.1007/s00018-014-1826-6 .
5. Mano N, de Poulpiquet A . O₂ Reduction in Enzymatic Biofuel Cells . Chemical Reviews . 118 . 5 . 2392–2468 . March 2018 . 28930449 . 10.1021/acs.chemrev.7b00220 .