Patent ID: 8691589

Claim:
A method for determining whether a target DNA forms a G-quadruplex in the presence of potassium ions, wherein the method comprises the following steps of: retaining a first sample solution containing potassium ions, thioflavin T and the target DNA under G-quadruplex forming reaction conditions; measuring a first fluorescence intensity value A at a wavelength of lambda 1, wherein the first fluorescence intensity value A is derived from thioflavin T contained in the first sample solution, and lambda 1 is 465 nanometers to 505 nanometers; retaining a second sample solution, independent of the first sample solution, containing thioflavin T and the target DNA under conditions for the G-quadruplex to be destabilized; measuring a second fluorescence intensity value B at the wavelength of lambda 1, wherein the second fluorescence intensity value B is derived from thioflavin T contained in the second sample solution; and determining that the target DNA forms the G-quadruplex in the presence of potassium ions if the following inequality is satisfied: the first fluorescence intensity value A −the second fluorescence intensity value B> 0.