Affinity modulation of small-molecule ligands by borrowing endogenous protein surfaces

Area of Science:

• Biochemistry
• Chemical Biology
• Drug Discovery

Background:

• Improving the binding affinity and specificity of small-molecule ligands to protein targets is a significant challenge in drug discovery.
• Existing methods often struggle with intractable targets, necessitating novel approaches.

Purpose of the Study:

• To develop a general strategy for enhancing the binding properties of small-molecule ligands to protein targets.
• To demonstrate the efficacy of this strategy using the challenging SH2 domain as a model target.

Main Methods:

• A bifunctional molecule was synthesized by chemically linking a ligand of interest to a second small molecule with high affinity for a distinct protein.
• This linked molecule facilitates the presentation of the ligand to its target protein via interactions with the second protein.
• The impact of induced protein-protein interactions on ligand-target binding affinity was analyzed.

Main Results:

• The bifunctional molecule approach demonstrated a 3-fold enhancement in binding affinity compared to the natural peptide for the SH2 domain.
• This strategy allows for modulation of binding affinity, either increasing or decreasing it based on the design.
• The method proved effective for an otherwise intractable protein target.

Conclusions:

• The described strategy offers a versatile method for improving small-molecule ligand binding to protein targets.
• This approach enhances ligand potency and specificity, providing a valuable tool for drug discovery and chemical biology.
• The successful application to the SH2 domain highlights the potential of this technique for challenging biological targets.