Reference:
S. Grzesiek and A. Bax (1992) J. Am. Chem. Soc. 114 6291-6293. (Link to Article)

Minimum labelling: ¹⁵N, ¹³C

Dimensions: 3

Magnetisation is transferred from ¹Hα and ¹Hβ to ¹³Cα and ¹³Cβ, respectively, and then from ¹³Cβ to ¹³Cα. From here it is transferred first to¹³CO, then to ¹⁵N^H and then to ¹H^N for detection. The chemical shift is evolved simultaneously on ¹³Cα and ¹³Cβ, so these appear in one dimension. The chemical shifts evolved in the other two dimensions are ¹⁵N^H and ¹H^N. The chemical shift is not evolved on ¹³CO.

Along with the CBCANNH and HSQC this forms the standard set of experiments needed for backbone assignment. For large proteins the signal-to-noise may not be great and assignment using the HNCA, HN(CO)CA, HNCO and HN(CA)CO may form a better strategy. When using deuterated protein, the spectrum has to be recorded as an ‘out-and-back’ method and the signal-to-noise suffers even further.