Assessment of human telomeric G-quadruplex structures using surface-enhanced Raman spectroscopy

Area of Science:

• Biophysical Chemistry
• Spectroscopy
• Molecular Biology

Background:

• G-quadruplexes (G4s) are nucleic acid structures implicated in various biological processes.
• The human telomeric sequence (Tel24) can form different G4 structures stabilized by specific cations.
• Understanding G4 structure is crucial for developing targeted therapeutics.

Purpose of the Study:

• To investigate the structural differentiation of G-quadruplexes formed by a human telomeric sequence using SERS spectroscopy.
• To identify specific SERS spectral signatures for different G4 topologies stabilized by sodium (Na+) and potassium (K+) ions.
• To evaluate the influence of SERS-active substrates on G4 structure and stability.

Main Methods:

• Surface-enhanced Raman scattering (SERS) spectroscopy was employed to analyze the Tel24 sequence.
• Citrate- and chloride-covered silver nanoparticles were used as SERS substrates.
• Circular dichroism (CD) spectroscopy was used to confirm structural integrity.

Main Results:

• Distinct SERS spectra were obtained for Tel24 in the presence of Na+ and K+.
• SERS bands characteristic of antiparallel basket-type (Na+) and hybrid (3+1) (K+) structures were identified.
• SERS analysis confirmed a consistent adsorption mechanism of cation-stabilized G4s onto silver surfaces without altering their stability.

Conclusions:

• SERS spectroscopy is a powerful tool for sensitive structural analysis of various G-quadruplex topologies.
• The study successfully differentiated and assigned specific G4 structures based on cation-induced stabilization.
• SERS provides valuable insights into the structural nuances of G-quadruplexes in solution and on surfaces.