(17)O NMR Spectroscopy: A Novel Probe for Characterizing Protein Structure and Folding

SIMPLE SUMMARY: Oxygen is one of the most abundant atoms in the body. Biomolecules, including most proteins, contain a significant number of oxygen atoms, contributing to the maintenance of the structural and functional integrity of biomolecules. Despite these favorable attributes, detailed characterization of these atoms has been challenging, particularly because of the lack of an appropriate analytical tool. Here, we review recent developments in biomolecular (17)O nuclear magnetic resonance spectroscopy, which can directly report the physicochemical properties of oxygen atoms in proteins or related biomolecules. We summarize recent studies that successfully employed this technique to elucidate various structural and functional features of proteins and protein complexes. Finally, we discuss a few promising benefits of this methodology, which we believe ensure its further development as a novel and powerful tool for investigating protein structure and folding. ABSTRACT: Oxygen is a key atom that maintains biomolecular structures, regulates various physiological processes, and mediates various biomolecular interactions. Oxygen-17 ((17)O), therefore, has been proposed as a useful probe that can provide detailed information about various physicochemical features of proteins. This is attributed to the facts that (1) (17)O is an active isotope for nuclear magnetic resonance (NMR) spectroscopic approaches; (2) NMR spectroscopy is one of the most suitable tools for characterizing the structural and dynamical features of biomolecules under native-like conditions; and (3) oxygen atoms are frequently involved in essential hydrogen bonds for the structural and functional integrity of proteins or related biomolecules. Although (17)O NMR spectroscopic investigations of biomolecules have been considerably hampered due to low natural abundance and the quadruple characteristics of the (17)O nucleus, recent theoretical and technical developments have revolutionized this methodology to be optimally poised as a unique and widely applicable tool for determining protein structure and dynamics. In this review, we recapitulate recent developments in (17)O NMR spectroscopy to characterize protein structure and folding. In addition, we discuss the highly promising advantages of this methodology over other techniques and explain why further technical and experimental advancements are highly desired.