Figure 2.

(A) Zoom of the tricyclic t6A residue (upper left). Side (right) and top view (lower left) of the loop region from the studied hairpin. Nucleobases of modified residue and the anticodon are depicted in green and yellow, respectively. A ribbon is drawn through P atoms. NOE distance restraints derived from NOE interactions of the threonine moiety in t⁶A37, are indicated in yellow dashed lines. Red dashed lines connect atoms that are within hydrogen bonding distance. Red circles highlight hydrogen bonds of the threonine moiety in t⁶A37 with other residues in the loop. (B) Strip of a noesy spectrum in D₂O (mix = 150 ms) at the resonance frequency of t6A37:H15, depicting some important NOEs in the loop region.