A Data Set of Simple 1-D and 2-D NMR Spectra of Peptides, including All Encoded Amino Acids, for Introductory Instruction in Protein Biomolecular NMR Spectroscopy

NMR spectroscopy is the most important technique for understanding the structure of peptides and proteins in solution. Contemporary publications in the interpretation of NMR spectra of peptides and proteins generally focus on advanced techniques and complex spectra, with a lack of simple spectra and guides available for beginning students. A data set of ¹H NMR spectra was generated from a series of simple peptides that include all canonical amino acids (<b>X</b>) [Ac-<b>X</b>(S/pS)-NH₂, Ac-<b>X</b>(T/pT)-NH₂, and Ac-<b>X</b>PPGY-NH₂; pS = phosphoserine, pT = phosphothreonine]. The characterization of each peptide includes 1-D and TOCSY spectra, with both raw and processed data available. The spectra can be used for instructional applications, including analysis of regions of the spectra (e.g., amide, aromatic, Hα, and aliphatic); identification of spin systems and residue assignment via TOCSY spectra; analysis of conformational features including amide H_N chemical shift dispersion and changes due to hydrogen bonding or post-translational modifications; the ³<i>J</i>_αN coupling constant that reports on the ϕ torsion angle and on order versus disorder at a residue; conformational preferences at Hα via chemical shift index analysis; understanding of diastereotopic hydrogens; dynamic processes, including hydrogen exchange; and identification of proline <i>cis</i>-<i>trans</i> isomerism. In addition, for a limited number of peptides, NOESY spectra are included to allow sequential resonance assignment and for assignment of <i>trans</i> versus <i>cis</i> proline conformations. Spectra from closely related peptides allow the analysis of the relative effects of single amino acid changes. The paper is written to be directly accessible to students in research laboratories or in the classroom as a tutorial guide.