Detection of protein cage assembly with bisarsenic fluorescent probes

We describe a method for the detection of specific protein-protein interactions in protein cages through the exploitation of designed binding sites for bisarsenic fluorescent probes. These sites are engineered to be protein-protein interface specific. We have adapted this method to ferritins; however, it could conceivably be applied to other protein cages. It is thought that this technique could be utilized in the thermodynamic and kinetic characterization of cage assembly mechanisms and in the high-throughput screening of protein cage libraries for the discovery of proteins with new assembly properties or of optimized conditions for assembly.