Solid state NMR structural evaluation of the SAF-p1/p2a co-assembling peptide nanofiber system

Abstract

This work presents a structural investigation of two variants of SAF (Self-Assembling Fiber) binary peptides designed by Prof. Derek N. Woolfson and coworkers. SAF refers to pairs of complementary peptides that assemble into coiled coils upon mixing, which then associate with one another to form fibers. Design features hypothesized to drive co-assembly were evaluated by solid-state nuclear magnetic resonance (NMR) spectroscopy. Our results indicate that the SAF assembly mechanism proposed by Woolfson is partially correct. However, it was also discovered that the α-helical structure formed by the initial co-assembly can undergo conversion to a β-sheet structure, and that this conversion is triggered by rehydration of the dried α-helical nanofibers. To our knowledge, this is the first α-β structural transition ever observed in response to physiologically benign stimuli in a co-assembling de novo binary peptide system.