Charge state heterogeneity in single alpha helices helps maintain helicity over a large range of pH values

Single Alpha Helices are repetitive, highly charged polyampholytes that exhibit a stable helical structure, despite having many characteristics of intrinsically disordered proteins. Previous studies have proposed that i, i+4 salt-bridges may be a key to the stabilization of the helical structure. However, measurements have also shown that SAHs can be stable over a large range of pH values, calling into question whether salt-bridges persist as stabilizing factors away from neutral pH values, and if they are the only contributors at neutral pH.