Base composition analysis of oligonucleotides containing apurinic sites

Area of Science:

• Biochemistry
• Organic Chemistry
• Analytical Chemistry

Background:

• Oligonucleotide synthesis involves chemical modifications that can affect their properties.
• High-Performance Liquid Chromatography (HPLC) is a key technique for analyzing synthesized oligonucleotides.
• Haptens like fluorescein and biotin are commonly used labels in molecular biology.

Purpose of the Study:

• To investigate the cause of an unexpected late-eluting peak observed in HPLC analysis of 3'-terminally labeled oligonucleotides.
• To determine the impact of hapten labels on oligonucleotide stability and enzymatic cleavage.
• To establish a method for monitoring acid-catalyzed depurination during oligonucleotide synthesis.

Main Methods:

• Base composition analysis of oligonucleotides.
• High-Performance Liquid Chromatography (HPLC) to analyze elution profiles.
• Enzymatic digestion using phosphodiesterase.
• Introduction of base-stable apurinic sites into oligonucleotide sequences.

Main Results:

• Oligonucleotides labeled with fluorescein or biotin at the 3'-terminus produced an additional, late-eluting peak in HPLC.
• The haptens (fluorescein, biotin) were identified as acting as apurinic sites.
• Phosphodiesterase cleavage was inhibited at the phosphate bond adjacent to the apurinic site.
• This effect was confirmed to be general using base-stable apurinic sites in various tetramer sequences.

Conclusions:

• Hapten labeling at the 3'-terminus of oligonucleotides can induce apurinic sites, hindering enzymatic cleavage.
• This phenomenon provides a novel method for monitoring acid-catalyzed depurination during oligonucleotide synthesis.
• Understanding these interactions is crucial for accurate oligonucleotide analysis and synthesis quality control.