Spontaneous assembly of a self-complementary oligopeptide to form a stable macroscopic membrane.

TLDR

The spontaneous membrane assembly of this peptide could serve as a model for insoluble peptides in neurological disorders and offers insights for biomaterials and origin‑of‑life studies. An important component of the stability is probably due to formation of complementary ionic bonds between glutamic and lysine side chains. The 16‑residue peptide [(Ala‑Glu‑Ala‑Glu‑Ala‑Lys‑Ala‑Lys)₂] adopts a β‑sheet conformation in water and, upon salt addition, spontaneously forms a heat‑ and chemical‑resistant macroscopic membrane composed of interwoven 10–20 nm filaments.

Abstract

A 16-residue peptide [(Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys)2] has a characteristic beta-sheet circular dichroism spectrum in water. Upon the addition of salt, the peptide spontaneously assembles to form a macroscopic membrane. The membrane does not dissolve in heat or in acidic or alkaline solutions, nor does it dissolve upon addition of guanidine hydrochloride, SDS/urea, or a variety of proteolytic enzymes. Scanning EM reveals a network of interwoven filaments approximately 10-20 nm in diameter. An important component of the stability is probably due to formation of complementary ionic bonds between glutamic and lysine side chains. This phenomenon may be a model for studying the insoluble peptides found in certain neurological disorders. It may also have implications for biomaterials and origin-of-life research.