Following G‐quartet formation by UV‐spectroscopy

TLDR

Oligodeoxynucleotides containing guanine stretches form a well‑known tetrameric G‑quartet structure. By measuring reversible absorbance changes at 295 nm, the method tracks intramolecular or intermolecular G‑quartet formation and dissociation. The 295 nm assay yields precise Tm and thermodynamic values, outperforms 260 nm measurements, and reveals an inverted denaturation profile in all tested G‑quartet oligonucleotides.

Abstract

Oligodeoxynucleotides which include stretches of guanines form a well-known tetrameric structure. We show that the recording of reversible absorbance changes at 295 nm allows to precisely monitor intramolecular guanine (G)-quartet formation and dissociation. Accurate Tm and thermodynamic values could be easily extracted from the data, whereas classical recordings at 260 nm led to a much larger uncertainty and in extreme cases, to completely inaccurate measurements. This inverted denaturation profile was observed for all G-quartet-forming oligonucleotides studied so far. This technique is very useful in all cases where intramolecular or intermolecular quadruplex formation is suspected.