Fig. 5.

Structure-guided functional optimization. (A) Schematic of 1301b_v1-ATP secondary structure shows 2′-O-Me modification on residues in the central junction (red). (B) ITC analysis of ATP binding of 1301b_v1 variants in 20 mM Mg²⁺. “#” means no binding. Data represent mean ± SD from three independent ITC measurements. The original ITC data are shown in SI Appendix, Figs. S27–S29. (C) ITC analysis of ATP binding of 9/10/16^OMe and 1301b_v1 under different Mg²⁺ concentrations. “#” means no binding. Data represent mean ± SD from three independent ITC measurements. The original ITC data are shown in SI Appendix, Fig. S30. The data of 1301b_v1 in (C) is identical to those of 1301b_v1 in Fig. 4C. (D) 1D ¹H NMR spectra show G H1 and T H3 signals of 9/10/16^OMe in 0/1/5/10/20 mM Mg²⁺ without adding ATP (Top five) and 20 mM Mg²⁺ with one equivalent of ATP (Bottom). [DNA] = 0.1 mM, [NaPi, pH 7] = 10 mM, [NaCl] = 50 mM, 90% H₂O/10% D₂O, T = 20 °C.