Sandbox Reserved 1104

This is a default text for your page '. Click above on edit this page' to modify. Be careful with the < and > signs.

You may include any references to papers as in: the use of JSmol in Proteopedia ^[1] or to the article describing Jmol ^[2] to the rescue.

Introduction

Structure

Multicopper oxidases are enzymes which oxidise their substrate by accepting electrons at a mononuclear copper centre and transferring them to a trinuclear copper centre.^[3]

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.^[4]

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.^[4]

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.^[4]

Function

Applications

3. Biofuel cell

In the field of power generation, biofuel cells provide an alternative to fossil energy. So far biofuell cells that were developed required specific enzymes that degrade and transform substrates present in physiologic fluids such as glucose and O2. These biofuel cells were used for medical devices power supply.^[5] Now a new generation of biofuel cells use hydrogenase. Indeed, H2/O2 biofuel cells are designed based on two thermostable enzymes: an hyperthermophilic O2-tolerant hydrogenase for H2 oxidation and bilirubin oxidase for O2 reduction. ^[6] Both enzymes are immobilized on carbon nanofibers. This biofuel cell can deliver electricity over a wide range of températures and pH. Indeed, the thermostability of the enzymes allows the biofuel cell to work under extreme conditions, from 30 to 80°C.^[5] H2/O2 biofuel cells can be used as alternative power supply for small electronic devices in a sustainable manner. However, research is ongoing; one issue is the enzyme instability on long term.^[6]

This is a sample scene created with SAT to by Group, and another to make of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.