Fig. 6. The 2′- and 3′-endo 2′dCTPs fitted into the omit map (3σ) of the RNAP-2′dCTP complex.

a The 3′OH group of the 2′-endo conformer is positioned to form up to three hydrogen bonds and a polar interaction with RNAP atoms (magenta lines, interatomic distances 2.5–3.1 Å). b The 3′OH of the 3′-endo conformer can hydrogen bond with one RNAP atom. The 2′- and 3′-endo conformers were derived from PDB IDs 2HVW (resolution: 1.67 Å) and 4DQI (resolution: 1.69 Å), respectively, and fitted into the omit map by rotating bonds but preserving bond lengths and angles. Source data are provided as a Source Data file.