Late stage modification of receptors identified from dynamic combinatorial libraries

Area of Science:

• Chemical Biology
• Molecular Recognition
• Biomolecular Engineering

Background:

• Small molecule receptors are crucial for detecting post-translational modifications like lysine methylation.
• Previous work identified receptors binding to trimethylated lysine (Kme3) with varying affinities and selectivities.

Purpose of the Study:

• To develop late-stage modification methods for Kme3 sensors.
• To synthesize biotinylated derivatives of existing and novel receptors for broader Kme3 sensing applications.

Main Methods:

• Dynamic combinatorial chemistry (DCC) for initial receptor identification.
• Late-stage functionalization via chemical modification (e.g., biotinylation).
• Synthesis of novel A2N variants using glycine-activated monomers.
• Isothermal Titration Calorimetry (ITC) and Nuclear Magnetic Resonance (NMR) for binding studies.

Main Results:

• Successful synthesis of biotinylated A2B, A2D, and A2G receptors.
• Development of a novel method for functionalizing the A2N receptor using glycine-activated monomers.
• Creation of A2N variants (A2Gly-N, Gly-A2N, Gly-A2Gly-N) enabling late-stage biotinylation.
• ITC and NMR data revealed that carboxylate spacing influences binding affinity and selectivity for KmeX guests.

Conclusions:

• Developed versatile, late-stage modification strategies for Kme3 sensors.
• Demonstrated the utility of glycine-activated monomers for functionalizing specific receptors like A2N.
• Established that carboxylate proximity plays a complex role in the molecular recognition of KmeX modifications.