Maleimide

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Maleimides

Maleimides are a group of organic compounds with a 2,5-pyrroledione skeleton. It is a contraction of maleic anhydride and an amide. The parent compound is 2,5-pyrroledione which in itself is a contraction of pyrrole and a ketone with the nitrogen atom carrying a proton but nitrogen is often N-substituted with alkyl or aryl groups such as a methyl or phenyl group. The substituent R can also be a polymer such as polyethylene glycol. Human hemoglobin chemically modified with maleimide-polyethylene glycol is a blood substitute called MP4 and can be used on anyone with any blood type.

[edit] Biotechnology Applications

Maleimides linked to polyethylene glycol chains are often used as flexible linking molecules to attach proteins to surfaces. The double bond readily reacts with the thiol group found on cysteine to form a stable carbon-sulfur bond. Attaching the other end of the polyethylene chain to a bead or solid support allows for easy separation of protein from other molecules in solution, provided these molecules do not also possess thiol groups.