1D and 2D 17O MAS NMR spectra of [U-13C,15N,70% 17O]-N-Ac-VL recorded at 35.2 T (ω0H/2π = 1500 MHz). Line structure (a) of N-Ac-VL illustrating the positions labeled with 17O (NCO, CO, and COH). Experimental (b) and simulated (c) 1D MAS 17O MAS NMR spectra, spinning at 19 kHz; centerbands indicated with asterisks (*). Slices (d) of the anisotropic dimension of the 2D 3QMAS spectrum of N-Ac-VL extracted at the isotropic frequency of the centerbands of each 17O moiety. (e) 2D 3QMAS spectrum of [U-13C, 15N, 70% 17O]-N-Ac-VL at 35.2 T (ω0H/2π = 1500 MHz) with the centerbands indicated with dashed horizontal lines and circles, the remaining peaks in the spectrum are due to spinning sidebands.