Metamorphic Proteins to Achieve Conformationally Selective Material Surface Binding

The controlled binding of proteins on nanoparticle surfaces remains a grand challenge required for many applications ranging from biomedical to energy storage. The difficulty in achieving this ability arises from the different functional groups of the biomolecule that can adsorb on the nanoparticle surface. While most proteins can only adopt a single structure, metamorphic proteins can access at least two different conformations, which presents intriguing opportunities to exploit such structural variations for binding to nanoparticles. Such effects are examined using calmodulin, a sensing messenger protein, that can adopt two conformations based on Ca²⁺ binding. The affinity of the apo and holo forms of the protein for Au is examined using a highly integrated set of experimental and computation studies, which demonstrated significantly enhanced binding for the holo protein as compared to the apo. Such effects are proposed to arise from changes in the protein structure, which lead to substantially varied biomolecular surfaces that facilitate both Au adsorption and protein-protein assembly once adsorbed. Such studies provide critical information for protein structural design to control nanoparticle adsorption for wide-ranging applications.