Self-Assembling Peptide Surfactants A(6)K and A(6)D Adopt α-Helical Structures Useful for Membrane Protein Stabilization

Elucidation of membrane protein structures have been greatly hampered by difficulties in producing adequately large quantities of the functional protein and stabilizing them. A(6)D and A(6)K are promising solutions to the problem and have recently been used for the rapid production of membrane-bound G protein-coupled receptors (GPCRs). We propose that despite their short lengths, these peptides can adopt α-helical structures through interactions with micelles formed by the peptides themselves. These α-helices are then able to stabilize α-helical motifs which many membrane proteins contain. We also show that A(6)D and A(6)K can form β-sheets and appear as weak hydrogels at sufficiently high concentrations. Furthermore, A(6)D and A(6)K together in sodium dodecyl sulfate (SDS) can form expected β-sheet structures via a surprising α-helical intermediate.