Role of Alkali Cations in DNA-Thioflavin T Interaction

Area of Science:

• Biophysical Chemistry
• Molecular Biology
• Spectroscopy

Background:

• Thioflavin T (ThT) is a fluorescent dye widely used in biophysical studies of amyloid proteins and nucleic acids.
• Understanding cation-DNA-dye interactions is crucial for accurate interpretation of ThT fluorescence data.

Purpose of the Study:

• To investigate the role of alkali cations (Na+, K+, Ca2+, Mg2+) in modulating the interaction between deoxyribonucleic acid (DNA) and Thioflavin T (ThT).
• To analyze the impact of these cations on ThT emission characteristics in the presence of double-stranded DNA and G-quadruplex structures.

Main Methods:

• Spectroscopic analysis of ThT emission in the presence of various DNA structures and cations.
• Lasing spectroscopy experiments to probe ThT sensitivity to the DNA hydration shell.

Main Results:

• Alkali cations modulate ThT emission in double-stranded DNA through direct binding and steric effects within the DNA hydration shell.
• ThT fluorescence is sensitive to the spatial arrangement of water molecules in the DNA hydration shell.
• Lasing was exclusively observed with Mg2+ in G-quadruplex structures, indicating an optimal environment for light amplification.

Conclusions:

• Cations play a critical role in DNA-ThT interactions, influencing dye binding and fluorescence properties.
• The G-quadruplex structure, particularly with Mg2+, creates conditions favorable for ThT-based light amplification.
• ThT remains a valuable tool in biophysical studies, with cation presence being a key consideration.