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

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 lip 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. (c) 2005 Wiley Periodicals, Inc.