Sample Preparation Procedures for High-Resolution Nuclear Magnetic Resonance Studies of Aqueous and Stabilized Solutions of Therapeutic Peptides

Abstract

This chapter covers the preparation of a purified nuclear magnetic resonance (NMR) peptide sample for analysis considering purity, pI, oxidation status, and solubility of the sample, along with the choice and preparation of the NMR sample tube. The NMR analysis of therapeutic peptides is an area that is still underdeveloped, but it offers both great promise and utility in drug screening and design (1–3). Ligand-target NMR-screening methods, such as saturation transfer difference NMR (STD-NMR;4) rely on correct NMR assignments of potential ligands to relate binding proximity to ligand-target structural arrangement. Furthermore, both nascent and stabilized therapeutic peptide structures from aqueous-based media can be related to binding efficacy and can enhance the design of future therapeutics via in silico analysis of data that is, in turn, reliant on correct NMR assignment. Accurate assignment and structural analysis of such peptides is ultimately obtained from high-quality NMR data that is achieved from meticulous sample preparation. It is feasible to run the necessary NMR experiments for the structural elucidation of a single high-quality 20-mer peptide sample in 12–18 h and to assign and obtain a structure from the data in 1–5 d. This is in contrast to the processes required for determining protein structures (5). The structural study of therapeutic peptides is long overdue as a routine analytical step and holds potential for the future. It is anticipated that the procedures described here will encourage research groups and scientists to prepare their peptides of interest for such structural work and present them to the high-resolution NMR facility in their organization for data acquisition and analysis.