Molecular complementarity and structural heterogeneity within co-assembled peptide β-sheet nanofibers

Area of Science:

• Biomaterials Science
• Supramolecular Chemistry
• Biophysics

Background:

• Self-assembling peptides are promising biomaterials for diverse applications.
• Charge-complementary peptides enable co-assembly into novel aggregate structures.
• Molecular-level organization of these co-assemblies remains poorly understood.

Purpose of the Study:

• To investigate the molecular organization of King-Webb (KW) peptide nanofibers.
• To elucidate the structural basis of co-assembly in charge-complementary peptide systems.

Main Methods:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.
• Discontinuous Molecular Dynamics (MD) simulations.
• Fourier Transform Infrared (FTIR) spectroscopy.

Main Results:

• KW+ and KW- peptides form near-stoichiometric, two-component β-sheet structures.
• A majority of β-strands exhibit antiparallel alignment, but significant parallel arrangements exist.
• Dipolar recoupling reveals non-negligible self-associated (AA and BB) pairs, challenging the ideal (AB)n pattern.
• Simulations predict coexistence of different structural motifs within the same nanofiber.

Conclusions:

• Charge-complementary peptide co-assemblies exhibit molecular-level structural disorder.
• The findings have implications for designing and engineering peptide-based biomaterials.
• Understanding this disorder is crucial for controlling the properties of co-assembled peptide systems.