The crystal structure of a collagen-model peptide [(Pro-Pro-Gly)(9)](3) has been determined at 1.33 A resolution. Diffraction data were collected at 100 K using synchrotron radiation, which led to the first structural study of [(Pro-Pro-Gly)(n)](3) under cryogenic conditions. The crystals belong to the P2(1) space group with cell parameters of a = 25.95, b = 26.56, c = 80.14 Angstroms and beta = 90.0 degrees. The overall molecular conformation was consistent with the left-handed 7/2-helical model with an axial repeat of 20 A for native collagen. A total of 332 water molecules were found in an asymmetric unit. Proline residues in adjacent triple-helices exhibited three types of hydrophobic interactions. Furthermore, three types of hydrogen-bonding networks mediated by water molecules were observed between adjacent triple-helices. These hydrophobic interactions and hydrogen-bonding networks occurred at intervals of 20 Angstroms along the c-axis based on the previous sub-cell structures [(Pro-Pro-Gly)(n)](3) (n = 9, 10), which were also seen in the full-cell structure of [(Pro-Pro-Gly)(10)](3). Five proline residues at the Y position in the X-Y-Gly triplet were found in a down-puckering conformation, this being inconsistent with the recently proposed propensity-based hypothesis. These proline residues were forced to adopt opposing puckering because of the prevailing hydrophobic interaction between triple-helices compared with the Pro:Pro stacking interaction within a triple-helix.
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==About this Structure==
==About this Structure==
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[[Category: Puckering]]
[[Category: Puckering]]
[[Category: Triple-helix]]
[[Category: Triple-helix]]
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Revision as of 22:05, 28 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
Full crystallographic information is available from OCA.
Reference
Repetitive interactions observed in the crystal structure of a collagen-model peptide, [(Pro-Pro-Gly)9]3., Hongo C, Noguchi K, Okuyama K, Tanaka Y, Nishino N, J Biochem. 2005 Aug;138(2):135-44. PMID:16091587
