Design and construction of an open multistranded β-sheet polypeptide stabilized by a disulfide bridge

Abstract

The design and characterization of an open eight-stranded β-sheet in a synthetic, 2-fold symmetric 70-residue peptide is described. The design strategy involves the generation of a 35-residue four-stranded β-sheet peptide in which successive hairpins are nucleated by appropriately positioned ^DPro-Xxx sequences. Oxidative dimerization using a single Cys residue positioned at the center of the C-terminal strand results in a disulfide-bridged eight-stranded structure. Nuclear Overhauser effects firmly establish an eight-stranded β-sheet in methanol. In water, the outer strands are frayed, but a well-defined four-stranded β-sheet stabilized by a disulfide bridge and a hydrophobic cluster is determined from NMR data. Comparison of the precursor peptide with the disulfide-bridged dimer reveals considerable enhancement of β-sheet content in the latter, suggesting that the disulfide cross-link is an effective strategy for the stabilization of β-sheets.