Photoswitching Affinity and Mechanism of Multivalent Lectin Ligands

Area of Science:

• Biochemistry
• Molecular Biology
• Supramolecular Chemistry

Background:

• Multivalent receptor-ligand interactions are crucial for biological recognition.
• Controlling ligand orientation can modulate binding affinity and mode.
• Photoswitchable molecules offer a way to dynamically alter molecular interactions.

Purpose of the Study:

• To design and synthesize a photoswitchable divalent ligand for wheat germ agglutinin (WGA).
• To investigate the effect of photoswitching on WGA binding affinity and mode.
• To evaluate the performance of an arylazopyrazole photoswitch in a biological system.

Main Methods:

• Synthesis of a divalent ligand incorporating an arylazopyrazole photoswitch.
• Isothermal titration calorimetry (ITC) to measure binding affinity.
• Dynamic light scattering (DLS) to assess binding mode (chelating vs. crosslinking).

Main Results:

• The photoswitchable ligand demonstrated nearly quantitative E/Z isomerization with high thermal stability.
• Photoswitching induced a significant change in WGA binding affinity.
• The E isomer favored chelating binding, while the Z isomer promoted crosslinking binding.

Conclusions:

• A novel photoswitchable ligand allows for dynamic control over WGA binding.
• Arylazopyrazole photoswitches are effective for modulating multivalent interactions.
• This approach provides a new tool for studying and engineering biological recognition.