Binding Assays Using a Benzofurazan-Labeled Fluorescent Probe for Estrogen Receptor-Ligand Interactions.

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• Estrogen receptor (ER) binding assays are crucial for assessing estrogenic activity.
• Traditional assays often require separation of free and bound ligands, complicating the process.
• Benzofurazan (BD) is a fluorophore whose properties are sensitive to environmental polarity.

Purpose of the Study:

• To develop novel fluorescent ligands for ER binding assays.
• To create a method for evaluating estrogenic compound affinity without ligand separation.
• To utilize the environmentally sensitive properties of benzofurazan (BD) for direct binding detection.

Main Methods:

• Synthesis of BD-labeled estradiol (E2) derivatives.
• Investigation of fluorescent ligand properties.
• Analysis of ligand-receptor interactions with human recombinant ERα (hr-ERα).
• Saturation and competitive binding assays.
• Comparison with fluorescence polarization methods.

Main Results:

• Three BD-skeleton fluorescent ligands were successfully synthesized.
• Fluorescence intensity increased in hydrophobic environments, like the ER binding site.
• Derivative 2c exhibited positive cooperative binding with a K_d of 23.4 nM and a Hill coefficient of 1.34.
• Assay results correlated well with conventional methods.

Conclusions:

• BD-labeled ligands provide a simple, rapid, and reliable method for ER binding affinity evaluation.
• The developed fluorescent assay eliminates the need for ligand separation.
• This approach offers a valuable tool for studying estrogenic compounds and ER interactions.