Triple Helical Stabilities of Guest–Host Collagen Mimetic Structures Original Research Article

The peptoid Nleu (N-isobutylglycine) has been successfully incorporated into a series of collagen mimetics composed of Gly-Pro-Nleu and Gly-Nleu-Pro sequences and has been able to maintain triple helices in appropriate structures. The achiral trimeric sequence Gly-Nleu-Nleu as a guest sequence in structures such as Ac-(Gly-Pro-Hyp)3-(Gly-Nleu-Nleu)3-(Gly-Pro-Hyp)3-NH2 retains triple helicity. As an extension of this study, we report, in this paper, on a series of guest–host collagen mimetic structures in which Gly-Nleu-Pro sequences are employed as the host. The guest sequences for these guest–host structures include Gly-Nleu-Nleu and Gly-Nx-Pro sequences where Nx is composed of a variety of alkyl and aralkyl peptoid residues. From these guest–host collagen mimetic structures, we are able to elucidate the contributions of hydrophobic and steric effects on triple helix formation. The Gly-Nleu-Pro sequences have been shown to be effective in inducing triple helicity. Conformational characterization of the guest–host collagen mimetic structures was established by techniques such as temperature-dependent optical rotation measurements and circular dichroism (CD) spectroscopy.