Weighting FID (indirect) C SOFAST-HMQC spectrum of 13 C, N]-labelled ubiquitin (277 K, 600 MHz) using NUWS and NUS reconstruction. (A) Weighted sampling scheme and apodization function used for acquisition. Points omitted for NUS reconstruction are indicated with orange shading. (B) C time domain signals (real part) acquired for the L50 δ 2 resonance (-0.23 1 H ppm) using uniform or non-uniform weighted sampling, with NUS reconstruction using SMILE . (C) 1 H, C SOFAST-HMQC spectra of ubiquitin acquired with uniform weighting (blue), and decoupled following NUWS acquisition and NUS reconstruction (red). Contour levels are normalised according to the number of scans in the first increment. A constant time HSQC spectrum (53.2 ms constant time period) is shown for comparison (green). Assignments from bmrb entry 6457. (D) C cross-sections indicated by dashed lines for the spectra shown in (C). is either not sufficient, or not available, for example in mammalian expressed proteins , or studies at natural isotopic abundance ; increasing the accuracy of frequency-based measurements of residual dipolar couplings; combination with homonuclear decoupling in the direct dimension and/or NUS or spectral aliasing to obtain ultra high-resolution 2D measurements ; sensitive and high-resolution analyses of the interactions of side-chains through titration experiments using uniformly 13C-labelled material; and as a simple approach to decouple Cα-Cβ scalar couplings in HNCA and other 3D experiments.