Figure 6.

Schematic representation of the 2D spectra based on ¹³C direct detection that can be used, in conjunction with the 2D HN (¹H–¹⁵N HSQC), to obtain a fingerprint of a protein. These include the 2D CON (¹³C′–¹⁵N correlation), 2D CACO (¹³C′–¹³C^α correlation), 2D CBCACO (¹³C′–¹³C^α and ¹³C′–¹³C^β correlations) spectra. The scalar couplings exploited to detect the correlations in the various spectra are schematically indicated in the top panel (¹J_NH, ¹J_C′N, ¹J_C′C^α, ¹J_C^αC^β). In addition to the correlations involving backbone nuclei shown in the figure, correlations involving specific side-chains can be observed (for Asn and Gln in HN and CON 2D spectra and for Asn/Asp and Gln/Glu in CACO and CBCACO 2D spectra). Adapted from ref (112). Copyright 2014, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.