Figure 7.

MAS NMR spectroscopy of N-Ac-VL: (a) ¹H direct Hahn-echo detection, (b) one-dimensional ¹H–¹⁷O R³-R-INEPT, (c) and two-dimensional ¹H–¹⁷O R³-R-INEPT spectrum with R³ = 100 μs. Spectra were acquired with ω_R/2π = 20 kHz at 17.6 T (ω_0H/2π = 750 MHz). Correlations between the leucine carbonyl proton to its directly bonded oxygen (blue arrow) and its next closest oxygen through space (NCO, green arrow) are indicated on the crystal structure of N-Ac-VL in the inset.⁹²