Generic assay format for endo- and exonucleases based on fluorogenic substrates labeled with single fluorophores

Area of Science:

• Molecular Biology
• Biochemistry
• Enzyme Assays

Background:

• Fluorogenic assays are crucial for studying nucleic acid-modifying enzymes.
• Previous work established assays using singly labeled synthetic oligonucleotides.

Purpose of the Study:

• To investigate how nucleotide sequence and fluorophore type affect singly labeled substrate performance.
• To develop an improved, generic fluorogenic assay format for various nucleic acid-modifying enzymes.

Main Methods:

• Systematic variation of nucleotide sequences near the fluorophore on synthetic oligonucleotide substrates.
• Evaluation of different fluorophores, including Oregon Green, for quenching efficiency.
• Development of a new generic substrate format adaptable to different enzyme recognition sequences.

Main Results:

• A 3' dC opposite a 5' dG maximized fluorophore quenching; additional 3' dC residues further enhanced quenching.
• Oregon Green demonstrated superior performance as a fluorophore in this assay format.
• The new generic format allows rapid substrate generation and exhibits expanded signal dynamic ranges compared to previous formats.

Conclusions:

• Optimized substrate design and fluorophore selection significantly enhance fluorogenic assay sensitivity.
• The developed generic assay format is versatile and applicable to a broad range of nucleic acid-modifying enzymes, including endonucleases, exonucleases, and DNA repair enzymes.