Triple helical stabilities of guest-host collagen mimetic structures

The peptoid Nleu (N-isobutylglycine) has been successfully incorporated int o a series of collagen mimetics composed of Gly-Pro-Nleu and Gly-Nleu-Pro s equences and has been able to maintain triple helices in appropriate struct ures. The achiral trimeric sequence Gly-Nleu-Nleu as a guest sequence in st ructures 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 t his paper, on a series of guest-host collagen mimetic structures in which G ly-Nleu-Pro sequences are employed as the host. The guest sequences for the se guest-host structures include Gly-Nleu-Nleu and Gly-N-x-Pro sequences wh ere N-x is composed of a variety of alkyl and aralkyl peptoid residues. Fro m these guest-host collagen mimetic structures, we are able to elucidate th e contributions of hydrophobic and steric effects on triple helix formation . The Gly-Nleu-Pro sequences have been shown to be effective in inducing tr iple helicity. Conformational characterization of the guest-host collagen m imetic structures was established by techniques such as temperature-depende nt optical rotation measurements and circular dichroism (CD) spectroscopy. (C) 1999 Elsevier Science Ltd. All rights reserved.