77Se NMR Spectroscopy of Selenoproteins
One of the most essential contributions of selenium to biology is the specialized chemistry performed by selenoproteins. Elucidating the mechanisms by which selenoproteins govern the reactivity of their selenocysteine (Sec) requires exploring how the prot
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Se NMR Spectroscopy of Selenoproteins
Jun Liu and Sharon Rozovsky
Abstract One of the most essential contributions of selenium to biology is the specialized chemistry performed by selenoproteins. Elucidating the mechanisms by which selenoproteins govern the reactivity of their selenocysteine (Sec) requires exploring how the protein environment primes Sec interactions with substrates, prevents inactivation, and otherwise optimizes the use of this unique amino acid. 77Se nuclear magnetic resonance (NMR) spectroscopy is a particularly powerful technique to study the chemical properties of selenocysteine, its conformational preferences and mobility, and the molecular interactions by which it is stabilized. Recent advances have simplified sample preparation and data analysis, extending the utilization of 77Se in NMR studies of biological samples. These improvements include the development of efficient procedures for enriching proteins with the 77Se isotope, the reports on NMR parameters of different selenoproteins that greatly expand the available basis for data analysis, and the progress in utilizing theoretical calculations for data interpretation. We discuss these areas of progress in 77Se NMR of biological systems, and we consider the range of questions for which 77Se NMR is most useful. Keywords 77Se NMR • Selenium NMR • Selenocysteine • Selenocystine • Selenopeptides • Selenoproteins • Selenoredox motifs
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NMR Spectroscopy of Biological Macromolecules
NMR spectroscopy is a superb probe of the molecular environment and an unparalleled tool for understanding its electronic and chemical structure. It is routinely used to study the atomic structures, conformational mobility, and supramolecular organization of biological macromolecules. In addition, it can characterize their interactions with ligands, drugs and protein partners. Routine biological NMR relies on the nuclei 1H, 13C, 15N, and 31P, whose behavior in different environments is extensively documented. Theoretical calculations allow the NMR observables of these nuclei in
J. Liu • S. Rozovsky (*) Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA e-mail: [email protected] © Springer Science+Business Media, LLC 2016 D.L. Hatfield et al. (eds.), Selenium, DOI 10.1007/978-3-319-41283-2_15
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different chemical environments to be predicted, and their relation to the structural and functional properties of macromolecules to be elucidated [1]. Biological NMR utilizes a variety of other, less ubiquitous nuclei (for example, metals) that yield rich information about function. Likewise, 77Se NMR is employed to study selenoproteins, since the chemistry centers on selenium’s high reactivity and thus it is advantageous to directly probe it. Furthermore, 77Se NMR is used as a spectroscopic surrogate of sulfur because the only NMR-sensitive isotope of sulfur, 33 S, is a low-sensitivity quadrupolar nucleus that cannot be utilized to study biological systems. This chapter focuses mostly on recent pr
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