Recent applications of isotopic labeling for protein NMR in drug discovery

Abstract

Introduction: Nuclear magnetic resonance (NMR) applications in drug discovery are classified into two categories: ligand-based methods and protein-based methods. The latter is based on the observation of the ¹H-¹⁵N HSQC spectra of a protein with and without lead compounds. However, in order to take this strategy, isotopic labeling is an absolute necessity. Given that each ¹H-¹⁵N HSQC signal corresponds to a residue of the target protein, signal changes provide specific information on whether a compound will fit into a pocket. Thus, this protein-based method is particularly suitable for fragment-based approaches, such as “SAR-by-NMR” and “fragment-growing.” Alternatively, the information from a protein interface may be used to develop inhibitors for protein–protein interactions.

Areas covered: This review discusses at the experimental procedures for preparing isotopically labeled protein and introduces selected topics on atom-specific and residue-selective isotope labeling, which may facilitate the development of PPI/PA inhibitors. Furthermore, the author reviews the recent applications of “in-cell” NMR spectroscopy, which is now considered as an important tool in drug delivery research.

Expert opinion: Many recent advances in labeling methods have succeeded in expanding NMR's potential for drug discovery. In addition to those methods, another new technique called “in-cell NMR” allows the observation of protein–ligand interactions inside living cells. In other words, “in-cell NMR” may become a pharmaceutical NMR technique for drug delivery.

Keywords::

• amino acid type-selective labeling
• fragment-based approach
• in-cell NMR
• inverse labeling
• protein-based method
• SAIL method

Acknowledgments

The author thanks K Sugiki and H Takahashi for helpful advice. The author also thanks Enago (www.enago.jp) for the English language review.

Notes

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