Functionalized Receptors for Efficient Epitope Recognition

PROJECT SUMMARY Biomedical science relies heavily on methods for attaching ligand binding sites to proteins. Such epitope tags are important for protein affinity purification, for improving protein solubility, and for adding functionality to proteins such as fluorescent labels or sites for chemical modification. The proposed research aims to develop synthetic receptors that target proteins engineered with efficient epitopes comprising only 2-3 amino acid residues. The epitopes are bound site-selectively and with subnanomolar affinity by small (1-2 kDa) monofunctional synthetic receptors with added ability to bind, fluoresce, or attach to solid supports. The receptors are stable and functional in physiological conditions, including serum, and proteins bound to these receptors can be released on demand upon the addition of small molecule competitors. The proposed aims will: 1) further optimize the epitopes; 2) install the epitopes into recombinant proteins and human insulin; and 3) develop monofunctional derivatives of the synthetic receptor to enhance binding and to enable affinity purification and protein sensing. The proposed epitopes will add function to target proteins while having minimal impact on structure and activity. The proposed work builds on the rules for sequence-selective recognition of peptides and proteins by cucurbit[n]urils established in the undergraduate research lab of the PI. Many research groups have developed applications built on these rules, and we anticipate that the proposed research will establish a core competency that should facilitate existing biomedical applications and inspire new ones.