4',6-Diamidino-2-phenylindole (DAPI) interacts with rare structures of GC polymers

Does the DNA Binding Mode of a Molecule Affect its Ability to Interact With Singlet Oxygen?

“…The minor groove binding mode is known to strongly enhance the fluorescence of DAPI (Fig. 4a) (28). A Scatchard analysis (46) of the data provided in Fig.…”

“…Regarding the binding mode of DAPI with GC sequences of DNA, a minor groove binding is sterically hindered by the 2‐amino group of guanine. Spectroscopic studies have strongly suggested an intercalative binding mode for DAPI in GC sequences (28,29). The fluorescence spectrum of DAPI complexed with GC is influenced by the sequence (28).…”

“…DAPI is commonly used to stain DNA in cytochemical studies (27). Its complexation with DNA was investigated and reviewed in various papers (28–31). X‐ray crystal structures have shown that DAPI binds in the minor groove of AT‐rich DNA segments (30,31).…”

“…X‐ray crystal structures have shown that DAPI binds in the minor groove of AT‐rich DNA segments (30,31). Spectroscopic studies strongly suggest an intercalative binding mode of DAPI with GC‐rich DNA segments (28,29). Although DAPI is known to bind to DNA with at least two different binding modes, the possible interaction of DAPI with 1 O 2 has never been investigated, though 1 O 2 is known to react efficiently with indole‐like structures (32,33).…”

“…The absorption ratios A 260 / A 280 ranged between 1.8 and 1.9 for the different samples, providing an estimation of the polynucleotide purity. A molar extinction coefficient of 23 000 m −1 cm −1 at 342 nm was used to determine the concentration of DAPI solution (28).…”