Design of a Three‐Helix Bundle Capable of Binding Heavy Metals in a Triscysteine Environment

A dream becomes reality : Until now, the engineering of novel metal‐binding sites into a three‐helix bundle has been an unrealized dream. By using an existing three‐helix bundle as a template, a 3‐Cys metal‐binding site was generated at the C‐terminal end by rational design to yield a well‐folded and stable construct that encapsulates the heavy metals Hg II , Cd II , and Pb II with high affinity and predefined coordination geometry (see picture).