Melanin production by tyrosinase activity on a tyrosine-rich peptide fragment and pH-dependent self-assembly of its lipidated analogue.

We investigate the self-assembly of a palmitoylated (C16-chain at the N terminus) peptide fragment in comparison to the unlipidated peptide EELNRYY, a fragment of the gut hormone peptide PYY3-36. The lipopeptide C16-EELNRYY shows remarkable pH-dependent self-assembly above measured critical aggregation concentrations, forming fibrils at pH 7, but micelles at pH 10. The parent peptide does not show self-assembly behaviour.

Self-Assembly of Lipopeptides Containing Short Peptide Fragments Derived from the Gastrointestinal Hormone PYY: From Micelles to Amyloid Fibrils.

We investigate the impact of lipidation on the self-assembly of two peptide fragments from the gastrointestinal peptide hormone PYY. The lipopeptides CIKPEAP and CIKPEAPGE contain the first 6 and 8 amino acid residues, respectively, from the PYY peptide sequence, with a palmitoyl C tail attached at the N-terminus. These lipopeptides form spherical micelles in aqueous solution, above a critical micelle concentration (cmc), which is pH-dependent.

The Effect of Lipidation on the Self-Assembly of the Gut-Derived Peptide Hormone PYY.

Lipidation is a powerful strategy to improve the stability in vivo of peptide drugs. Attachment of a lipid chain to a hydrophilic peptide leads to amphiphilicity and the potential for surfactant-like self-assembly. Here, the self-assembly and conformation of three lipidated derivatives of the gastrointestinal peptide hormone PYY is examined using a comprehensive range of spectroscopic, scattering, and electron microscopy methods and compared to those of the parent PYY peptide.

The design and fabrication of supramolecular semiconductor nanowires formed by benzothienobenzothiophene (BTBT)-conjugated peptides.

π-Conjugated small molecules based on a [1]benzothieno[3,2-b]benzothiophene (BTBT) unit are of great research interest in the development of solution-processable semiconducting materials owing to their excellent charge-transport characteristics. However, the BTBT π-core has yet to be demonstrated in the form of electro-active one-dimensional (1D) nanowires that are self-assembled in aqueous media for potential use in bioelectronics and tissue engineering. Here we report the design, synthesis, and self-assembly of benzothienobenzothiophene (BTBT)-peptide conjugates, the BTBT-peptide (BTBT-C3-COHN-Ahx-VVAGKK-Am) and the C8-BTBT-peptide (C8-BTBT-C3-COHN-Ahx-VVAGKK-Am), as β-sheet forming amphiphilic molecules, which self-assemble into highly uniform nanofibers in water with diameters of 11-13(±1) nm and micron-size lengths.

Shear Alignment of Bola-Amphiphilic Arginine-Coated Peptide Nanotubes.

The bola-amphiphilic arginine-capped peptide RFLRF self-assembles into nanotubes in aqueous solution. The nanostructure and rheology are probed by in situ simultaneous rheology/small-angle scattering experiments including rheo-SAXS, rheo-SANS, and rheo-GISANS (SAXS: small-angle X-ray scattering, SANS: small-angle neutron scattering, GISANS: grazing incidence small-angle neutron scattering). Nematic alignment of peptide nanotubes under shear is observed at sufficiently high shear rates under steady shear in either Couette or cone-and-plate geometry.

Nanosheet Formation by an Anionic Surfactant-like Peptide and Modulation of Self-Assembly through Ionic Complexation.

The surfactant-like peptide (Ala)-(Asp) (AD) is shown to self-assemble into ultrathin (3 nm thick) nanosheets in aqueous solution above a critical aggregation concentration. A combination of circular dichroism and FTIR spectroscopy and X-ray diffraction shows that the nanosheets comprise interdigitated bilayers of the peptide with β-sheet conformation. The self-assembly can be modulated by addition of hexamethylenediamine which is expected to interact with the anionic C terminus (and C-terminal D residue) of the peptide.