To determine the structures of peptides and proteins using BioNMR, the protein must be labeled with 15N and 13C to enable analysis of 2D NMR spectra at the atomic level. This can be achieved by expressing the protein in E. coli using established protocols, in which 15N-labeling is not significantly more expensive than standard E. coli expression. 15N-labeling is generally adequate for conducting 2D NMR fragment screening and confirming the folding status of protein constructs. Depending on the specific project, additional isotope labeling may be necessary, particularly for larger proteins, which often produce clearer NMR spectra when labeled with 2H. Expression and purification of 2H, 15N, and 13C-labeled protein in E.coli for NMR spectroscopy studies and structure determination.
