Sandbox Reserved 1104: Difference between revisions

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Multicopper oxidases are enzymes which oxidise their substrate by accepting electrons at a mononuclear copper centre and transferring them to a trinuclear copper centre.<ref>Wikipedia, Multicopper oxidase [https://en.wikipedia.org/wiki/Multicopper_oxidase]</ref>

Bilirubin oxidases are multicopper oxidases containing type 1, type 2, and type 3 coppers. Indeed, there is strong sequence homology between bilirubin oxidase and multicopper oxidases like laccase, ascorbate oxidase and even ceruloplasmin. Moreover, the His-Cys-His sequence, characteristic of multicopper oxidase, is present in bilirubin oxidase. Copper is essential for the enzyme activity.<ref>DOI 10.1021/bi9819531</ref>

Bilirubin oxidases are multicopper oxidases containing type 1, type 2, and type 3 coppers. Indeed, there is strong sequence homology between bilirubin oxidase and multicopper oxidases like laccase, ascorbate oxidase and even ceruloplasmin. Moreover, the His-Cys-His sequence, characteristic of multicopper oxidase, is present in bilirubin oxidase. Copper is essential for the enzyme activity.<ref name="multic">DOI 10.1021/bi9819531</ref>

Copper is classified into three types according to their optical and magnetic properties. Type 1 copper (or blue copper) shows many charge-transfer bands around 450 nm, 600 nm and 750 nm. The most peculiar band appears around 600 nm and represents the Cys to Cu(II) charge transfer. Type 2 copper (or nonblue copper) does not show any strong charge-transfer bands in the visible region. Type 3 coppers are not detectable by ESR because some are antiferromagnetically coupled. However, a hydroxide ion links them and so gives a strong absorption at 330 nm.<ref name="multic"/>

While type 2 and 3 coppers reduce dioxygen to two water molecules by forming a trinuclear center, type 1 copper transfers electrons from substrate to the trinuclear center. This is the peculiar sequence His456-Cys457-His458 that forms an intramolecular electron-transfer pathway between the type 1 copper site and the trinuclear center composed of the type 2 and type 3 copper sites.<ref name="multic"/>

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 Multicopper oxidases are enzymes which oxidise their substrate by accepting electrons at a mononuclear copper centre and transferring them to a trinuclear copper centre.<ref>Wikipedia, Multicopper oxidase [https://en.wikipedia.org/wiki/Multicopper_oxidase]</ref>
-Bilirubin oxidases are multicopper oxidases containing type 1, type 2, and type 3 coppers. Indeed, there is strong sequence homology between bilirubin oxidase and multicopper oxidases like laccase, ascorbate oxidase and even ceruloplasmin. Moreover, the His-Cys-His sequence, characteristic of multicopper oxidase, is present in bilirubin oxidase. Copper is essential for the enzyme activity.<ref>DOI 10.1021/bi9819531</ref>
+Bilirubin oxidases are multicopper oxidases containing type 1, type 2, and type 3 coppers. Indeed, there is strong sequence homology between bilirubin oxidase and multicopper oxidases like laccase, ascorbate oxidase and even ceruloplasmin. Moreover, the His-Cys-His sequence, characteristic of multicopper oxidase, is present in bilirubin oxidase. Copper is essential for the enzyme activity.<ref name="multic">DOI 10.1021/bi9819531</ref>
+Copper is classified into three types according to their optical and magnetic properties. Type 1 copper (or blue copper) shows many charge-transfer bands around 450 nm, 600 nm and 750 nm. The most peculiar band appears around 600 nm and represents the Cys to Cu(II) charge transfer. Type 2 copper (or nonblue copper) does not show any strong charge-transfer bands in the visible region. Type 3 coppers are not detectable by ESR because some are antiferromagnetically coupled. However, a hydroxide ion links them and so gives a strong absorption at 330 nm.<ref name="multic"/>
+While type 2 and 3 coppers reduce dioxygen to two water molecules by forming a trinuclear center, type 1 copper transfers electrons from substrate to the trinuclear center. This is the peculiar sequence His456-Cys457-His458 that forms an intramolecular electron-transfer pathway between the type 1 copper site and the trinuclear center composed of the type 2 and type 3 copper sites.<ref name="multic"/>
 == Function ==