Development of a novel β-secretase binding assay using the AlphaScreen platform

Area of Science:

• Biochemistry
• Neuroscience
• Assay Development

Background:

• Alzheimer's disease (AD) is a major neurodegenerative disorder.
• Beta-secretase-1 (BACE1) is a validated therapeutic target for AD due to its role in amyloid-beta (Aβ) production.
• High-throughput screening (HTS) is crucial for discovering novel AD drug candidates.

Purpose of the Study:

• To develop and validate a novel, high-throughput screening-amenable binding assay for BACE1.
• To assess the utility of the assay for identifying small-molecule BACE1 inhibitors.
• To optimize assay conditions for sensitivity and reliability.

Main Methods:

• Development of a novel AlphaScreen binding assay utilizing streptavidin donor and nickel-chelate acceptor beads.
• Functionalization of BACE1 inhibitors (hydroxyethylamine, hydantoin, sulfamide classes) with biotin PEG linkers to create probes.
• Optimization of assay conditions and miniaturization to a 1536-well format for HTS.

Main Results:

• The AlphaScreen assay demonstrated high signal-to-background ratios for BACE1 inhibitors from multiple chemical classes.
• Optimized assay conditions (50 nM BACE1, 250 nM probe) yielded Z' values >0.75.
• The AlphaScreen assay showed approximately 10-fold greater sensitivity compared to a fluorescence polarization assay.
• The assay was successfully applied to screen 525,000 compounds.

Conclusions:

• A robust and sensitive AlphaScreen binding assay for BACE1 was successfully developed and validated.
• The assay is suitable for HTS and effective in identifying BACE1 inhibitors.
• This assay represents a valuable tool for accelerating the discovery of novel Alzheimer's disease therapeutics.