Controlled Self‐Assembly of Re‐engineered Insulin by FeII

Self‐assembly of proteins mediated by metal ions is crucial in biological systems and a better understanding and novel strategies for its control are important. An abiotic metal ion ligand in a protein offers the prospect of control of the oligomeric state, if a selectivity over binding to the native side chains can be achieved. Insulin binds ZnII to form a hexamer, which is important for its storage in vivo and in drug formulations. We have re‐engineered an insulin variant to control its self‐assembly by covalent attachment of 2,2′‐bipyridine. The use of FeII provided chemoselective binding over the native site, forming a homotrimer in a reversible manner, which was easily followed by the characteristic color of the FeII complex. This provided the first well‐defined insulin trimer and the first insulin variant for which self‐assembly can be followed visually.
Keyword: Self-assembly,Protein–protein interactions,Iron,Insulin,Bipyridine