(A) A
G-tetrad with detectable H1–H1 and H1–H8 NOE
connectivity. (B) Imino H1 and aromatic H8 proton assignments of Pu30_3T4AA
by 1D 15N-filtered experiments using site-specific labeled
oligonucleotides at 25 °C. (C) Schematic drawing of the folding
topology of the major G-quadruplex 1245G4 formed in the BCL-2 promoter
sequence Pu30 (G = red, A = green, C = yellow). (D) H1–H1 region
and (E) H1–H8 region of the 2D-NOESY spectrum of Pu30_3T4AA
in H2O at 5 °C with a mixing time of 200 ms. The proton
assignments are shown on the sides. Intratetrad NOEs are in red, intertetrad
NOEs in blue, sequential intertetrad NOEs in black, and NOEs with
flanking bases in green. Conditions: 25 mM K-phosphate, 70 mM KCl,
pH 7.0.