Backbone Nitrogen Substitution Restricts the Conformation of Glycine Residues in Protein β-Turns

Glycine adopts backbone conformations that are generally inaccessible to other amino acids, but specifying a particular conformation remains challenging. Inspired by studies of small-molecule models, we hypothesized that substituting the alpha carbon with nitrogen would bias glycine toward specific β-turn conformations, which we confirmed through biophysical analysis of backbone-modified peptides.