Conformation of alloHyp in the Y position in the host-guest peptide with the pro-pro-gly sequence: implication of the destabilization of (Pro-alloHyp-Gly)10

Abstract

The crystal structure of the host-guest peptide, (Pro-Pro-Gly)4-(Pro-alloHyp-Gly)-(Pro-Pro-Gly)4, was analyzed at high resolution. allohydroxyproline (alloHyp), 4S-hydroxyproline, was successfully characterized through the use of a host-guest peptide, while the previous study indicated the inability of a triple helical formation of (Pro-alloHyp-Gly)10. A detailed analysis of alloHyp conformation in collagen-like models sheds light on the role played by its puckering in the triple-helix stabilization and destabilization. That is, the alloHyp typically adopts down puckering. However, it adopted up puckering in the Y position in the Pro-alloHyp-Gly guest triplet, which was not preferable conformation for alloHyp. Therefore, the energetically unfavorable conformations seemed to play the key role in giving destabilization to the triple helix in (Pro-alloHyp-Gly)10. The intrinsic hydration pattern in (Pro-Pro-Gly)9 was conserved even in the surrounding alloHyp residues.