Accurate ¹³C-¹⁵N Distance Measurements in Uniformly ¹³C,¹⁵N-Labeled Peptides

Abstract

The ability to accurately measure ¹³C-¹⁵N dipolar couplings corresponding to internuclear distances in the 3–6 Å regime is important for constraining the three-dimensional structure of biological solids. Solid-state NMR (SSNMR) methods for heteronuclear distance measurements in isolated spin pairs are now well-established and will continue to provide valuable structural information [1,2]. However, these methods require synthesis of molecules isotopically labeled in a pairwise fashion, which can be both laborious and expensive. Thus, there is a clear motivation for the development of analogous SSNMR methods for larger spin systems, where multiple internuclear distances can be determined [3–5]. However, in multispin systems ¹³C-¹⁵N distance measurements have the potential to be complicated by the presence of multiple homonuclear and heteronuclear spin-spin couplings.