Crystal structure of a collagen-like polypeptide with repeating sequence Pro-Hyp-Gly at 1.4 resolution: Implications for collagen hydration

Abstract

The use of polypeptide models has proved to be a valuable tool to obtain accurate information on the collagen triple helix. Here we report the high resolution crystal structure of a collagen-like polypeptide with repeating sequence Pro–Hyp–Gly. The structure has been refined to an R_factor of 0.137 and an R_free of 0.163 using synchrotron diffraction data extending up to 1.4 Å resolution. The polypeptide triple-helical structure binds a large number of water molecules, in contrast with a previous structure determination at lower resolution. The highly hydrated nature of this polypeptide confirms a number of previous studies conducted both in solution and in the crystal state. In addition, neighboring polypeptide triple helices are directly bound in the crystal through Hyp–Hyp hydrogen-bonding interactions. This finding supports the idea that Hyp residues may be important for the assembly of the triple helices in the collagen fibrils and may stabilize the fibrils by mediating direct contacts between neighboring molecules. © 2001 John Wiley & Sons, Inc. Biopolymers 56: 8–13, 2001