Parallel multiplex thermodynamic analysis of coaxial base stacking in DNA duplexes by oligodeoxyribonucleotide...

Area of Science:

• Molecular Biology
• Biophysics
• Chemical Biology

Background:

• DNA duplex stability is influenced by base stacking interactions.
• Understanding these interactions is crucial for DNA-based technologies.
• Microchip-based arrays offer a novel platform for thermodynamic analysis.

Purpose of the Study:

• To investigate the coaxial stacking effect of DNA bases using microchip technology.
• To quantify the thermodynamic parameters of base stacking in various sequence contexts and with modified bases.
• To compare microchip-based measurements with traditional solution-based methods.

Main Methods:

• Oligonucleotides were immobilized on microchips (MAGIChips') in polyacrylamide gel pads.
• Melting temperatures and free energies of DNA duplexes were measured to assess stacking.
• All base combinations, including mismatches and gaps, were analyzed.
• Oligonucleotides were modified with various chemical groups (e.g., FITC, Texas Red, acridine).

Main Results:

• Microchip-derived thermodynamic parameters for stacking closely matched solution data.
• Oligonucleotide modifications with 5,6-dihydroxyuridine, phosphate, FITC, or Texas Red altered stacking effects.
• Acridine and 5-nitroindole modifications enhanced stacking at specific interfaces.
• High salt concentrations (5 M tetramethylammonium chloride) equalized melting temperatures but reduced stacking energy.

Conclusions:

• Microchip-based thermodynamic analysis is a reliable method for studying DNA base stacking.
• Chemical modifications significantly modulate DNA stacking interactions and duplex stability.
• Environmental factors, such as salt concentration, influence stacking thermodynamics.