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Bio-sulphur for a healthy liver

Copper is a trace element, essential to all living cells. However, an excess of this metal can induce severe diseases. The SCIB has designed a sulfur-rich bio-mimetic molecule, able to selectively encapsulate copper. This work opens the route to an efficient and targeted treatment of copper overload in the liver, and therefore to an improvement in patient comfort.

Published on 20 November 2009
Copper plays a role in many biological processes, such as oxygen transport or the reduction of oxygen in water. However, copper overload in the body is very toxic and leads to severe problems in both the liver and in the nervous system. For instance, Wilson’s disease is one of the major genetic disorders of Cu metabolism in humans (1 over 40 000 people). Soluble copper exists in two oxidized states: Cu(II) and Cu(I). In food, it is present as Cu(II), which is more stable in air. In cells, copper is present as Cu(I) and therefore has a great affinity for sulfur-based compounds. That’s why copper trafficking and sequestering proteins have a large number of amino acids containing sulfur atoms: cysteins.

We have designed a molecule to encapsulate copper in cells, and promote its elimination. This molecule derives from a compound known to bind calcium and magnesium, for instance in washing powders, and is functionalized with three cysteins. This molecule shows a very high affinity for Cu(I) in vitro, without interfering with other ions present in cells like zinc(II). To use this system in vivo, the copper-binding molecule will be functionalized with a recognition unit to selectively target it to hepatic cells.

Copper encapsulation by our ligand.
The “pincer” formed by the 3 cysteins (orange) captures copper in Cu(I) state (green) thanks to the three sulfur atoms (yellow).

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