Fig. 1. (A) Zoom in of the 1H–13C HSQC without proton decoupling for: H-SGR(α-Rha)NAAVVK-OH (14), 1 J CH = 167 Hz (left) and H-SGR(β-Rha)NAAVVK-OH (15), 1 J CH = 156 Hz (right); (B) selective ROESY experiments for H-SGR(β-Rha)NAAVVK-OH (15). Black = zoom in of 1H NMR spectrum, blue = selected ROESY by irradiating H-1; red: selected ROESY by irradiating H5. The through-space NOE relationship between diaxial H5 and H1 can be observed; (C) selective ROESY experiments for H-SGR(α-Rha)NAAVVK-OH (14). Black = zoom in of 1H NMR spectrum, blue = selected ROESY by irradiating H-5; red: selected ROESY by irradiating H1. No NOE was observed; (D) analytical HPLC traces of H-SGR(α-Rha)NAAVVK-OH 14 (top), H-SGR(β-Rha)NAAVVK-OH 15 (middle), overlay of HPLC chromatograms of 14 and 15 (bottom); gradient: 100% A for 2 min then 0–20% B over 30 min, Waters Atlantis® T3 C18 Column at 0.2 mL min–1.
