3 research outputs found
Self-Assembly of an α‑Helical Peptide into a Crystalline Two-Dimensional Nanoporous Framework
Sequence-specific peptides have been
demonstrated to self-assemble into structurally defined nanoscale
objects including nanofibers, nanotubes, and nanosheets. The latter
structures display significant promise for the construction of hybrid
materials for functional devices due to their extended planar geometry.
Realization of this objective necessitates the ability to control
the structural features of the resultant assemblies through the peptide
sequence. The design of a amphiphilic peptide, <b>3FD-IL</b>, is described that comprises two repeats of a canonical 18 amino
acid sequence associated with straight α-helical structures.
Peptide <b>3FD-IL</b> displays 3-fold screw symmetry in a helical
conformation and self-assembles into nanosheets based on hexagonal
packing of helices. Biophysical evidence from TEM, cryo-TEM, SAXS,
AFM, and STEM measurements on the <b>3FD-IL</b> nanosheets support
a structural model based on a honeycomb lattice, in which the length
of the peptide determines the thickness of the nanosheet and the packing
of helices defines the presence of nanoscale channels that permeate
the sheet. The honeycomb structure can be rationalized on the basis
of geometrical packing frustration in which the channels occupy defect
sites that define a periodic superlattice. The resultant 2D materials
may have potential as materials for nanoscale transport and controlled
release applications
Rational Design of Helical Nanotubes from Self-Assembly of Coiled-Coil Lock Washers
Design
of a structurally defined helical assembly is described
that involves recoding of the amino acid sequence of peptide <b>GCN4-pAA</b>. In solution and the crystalline state, <b>GCN4-pAA</b> adopts a 7-helix bundle structure that resembles a supramolecular
lock washer. Structurally informed mutagenesis of the sequence of <b>GCN4-pAA</b> afforded peptide <b>7HSAP1</b>, which undergoes
self-association into a nanotube via noncovalent interactions between
complementary interfaces of the coiled-coil lock-washer structures.
Biophysical measurements conducted in solution and the solid state
over multiple length scales of structural hierarchy are consistent
with self-assembly of nanotube structures derived from 7-helix bundle
subunits. The dimensions of the supramolecular assemblies are similar
to those observed in the crystal structure of <b>GCN4-pAA</b>. Fluorescence studies of the interaction of <b>7HSAP1</b> with
the solvatochromic fluorophore PRODAN indicated that the nanotubes
could encapsulate shape-appropriate small molecules with high binding
affinity
Rational Design of Helical Nanotubes from Self-Assembly of Coiled-Coil Lock Washers
Design
of a structurally defined helical assembly is described
that involves recoding of the amino acid sequence of peptide <b>GCN4-pAA</b>. In solution and the crystalline state, <b>GCN4-pAA</b> adopts a 7-helix bundle structure that resembles a supramolecular
lock washer. Structurally informed mutagenesis of the sequence of <b>GCN4-pAA</b> afforded peptide <b>7HSAP1</b>, which undergoes
self-association into a nanotube via noncovalent interactions between
complementary interfaces of the coiled-coil lock-washer structures.
Biophysical measurements conducted in solution and the solid state
over multiple length scales of structural hierarchy are consistent
with self-assembly of nanotube structures derived from 7-helix bundle
subunits. The dimensions of the supramolecular assemblies are similar
to those observed in the crystal structure of <b>GCN4-pAA</b>. Fluorescence studies of the interaction of <b>7HSAP1</b> with
the solvatochromic fluorophore PRODAN indicated that the nanotubes
could encapsulate shape-appropriate small molecules with high binding
affinity