Supramolecular Assembly of Electrostatically Stabilized, Hydroxyproline-Lacking Collagen-Mimetic Peptides

Abstract

The mechanical and biological functions of the native collagens remain an inspiration in materials design, but widespread application of de novo collagens has been limited in part by the need for hydroxylated proline in the formation of stable triple helical structures. To address this continued need and to expand the potential for recombinant expression of functional, hydroxyproline-lacking collagen-mimetic peptides, we have designed a hydrophilic, nonrepetitive, and thermally stable collagen-mimetic peptide via the incorporation of triple-helix-stabilizing charged triplets. The peptide sequence is also equipped with a type III-collagen-mimetic cystine knot at the C-terminus to facilitate covalent cross-linking of the triple helix via simple air oxidation. Circular dichroic spectroscopy (CD) studies of this collagen-mimetic peptide revealed a typical, thermally stable, collagen triple helix signature with a weak positive maximum at 225 nm and a triple helix melting temperature (T(m)) of 35 and 43 degrees C for the reduced and oxidized forms, respectively. The thermal behavior was confirmed via analysis by differential scanning calorimetry. Interestingly, this hydroxyproline-lacking, collagen-mimetic peptide also assembles into nanorods and microfibrillar structures as observed via transmission electron microscopy. The identification and demonstrated useful collagen-mimetic properties of this peptide suggests important opportunities in the recombinant design of new collagen-based biomaterials.