Crystal structure of the collagen triple helix model [(Pro‐Pro‐Gly)10]3

Abstract

The first report of the full-length structure of the collagen-like polypeptide [(Pro-Pro-Gly)₁₀]₃ is given. This structure was obtained from crystals grown in a microgravity environment, which diffracted up to 1.3 Å, using synchrotron radiation. The final model, which was refined to an R_factor of 0.18, is the highest-resolution description of a collagen triple helix reported to date. This structure provides clues regarding a series of aspects related to collagen triple helix structure and assembly. The strict dependence of proline puckering on the position inside the Pro-Pro-Gly triplets and the correlation between backbone and side chain dihedral angles support the propensity-based mechanism of triple helix stabilization/destabilization induced by hydroxyproline. Furthermore, the analysis of [(Pro-Pro-Gly)₁₀]₃ packing, which is governed by electrostatic interactions, suggests that charges may act as locking features in the axial organization of triple helices in the collagen fibrils.