Fig. 7: Automatic picking of 3 and 4D methyl NOE spectra.

Results from a 3D methyl NOESY spectrum from ATCase (a) and a 4D methyl NOESY spectrum of EIN (b). These figures were generated from outputs within our GUI. (i) The location of two selected slices is indicated with respect to the relevant projections. It is desirable when analysing 4D spectra to take 2D slices that have lower resolution than the reference planes that include the direct dimension, as shown for EIN. (ii) The corresponding slices focusing on identified NOEs from a pair of resonances, and a cross peak between them. The specific cross peak feature is indicated (orange). Orthogonal views can be selected within the GUI allowing a user to verify that all resonances are centred on the selected plane. The deconvolved version of the spectrum can also be shown side-by-side with the raw data. (iii) The cross peak signal intensity, shown as a mean and standard deviation of the two reciprocal resonances, shown versus the expected C-C distance from the corresponding structure. 460 pairs of cross-peaks were identified for ATCase and 660 for EIN, overall 60% more than obtained from a manual analysis²⁹ (294, 420 respectively). The picked peaks fall within a sensible range of distances indicating that the NOEs are consistent with the expected structures (iii).