Intramolecular interactions of selenomethionine in proteins: expanding the applications of 77Se NMR in biological macromolecules
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Selenium plays an essential role in the proper function of human physiology in the form of the uncommon amino acid selenomethionine (SeM), in which the sulfur atom in the side chain of methionine (Met) is replaced by a selenium atom in the same position. In an effort to better understand the dynamics of how selenium plays an essential role in proper physiological function, it was first necessary to understand the fundamental interactions that selenium experiences within its local environment in proteins. Selenium, in the form of its 77Se isotope, exists in nature at 7.6% natural abundance and has an intrinsic spin of ½, which makes it an ideal candidate for nuclear magnetic spectroscopy (NMR). NMR serves as a powerful tool for measuring a diverse range of chemical properties, including the response of a nucleus to its local environment through a number of different interactions. These interactions, such as solvent effects and various intramolecular interactions, can be effectively introduced via a rationally designed model system. This approach was carried out through the incorporation of a selenomethionine residue at six different positions within the well-characterized model protein, the β1 immunoglobulin binding domain of Protein G (GB1). Each of the selenomethionine substitutions were made at a location within the tertiary structure of GB1 that promoted a different chemical environment in order to better understand how selenium responds to these local environments. These six selenomethionine-containing GB1 variants were then evaluated using a range of one-dimensional and two-dimensional NMR studies, which yielded a broad library of information that provided a new understanding of how selenium interacts in different chemical environments.
Description
Keywords
Selenomethionine, Proteins