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

The use of polypeptide models has proved to be a valuable tool to obtain ac curate information on the collagen triple helix. Here we report the high re solution crystal structure of a collagen-like polypeptide with repeating se quence Pro-Hyp-Gly. The structure has been ri fined to an R-factor of 0.137 and an R-free of 0.163 using,synchrotron diffraction data extending iq) to 1.4 Angstrom resolution. The polypeptide triple-helical structure binds a large number of water molecules, in contrast with a previous structure dete rmination at lower resolution. The highly hydrated nature of this polypepti de confirms a number of previous studies conducted both in solution and in the crystal state. In addition, neighboring polypeptide triple helices are directly in bound in the crystal through Hyp-Hyp hydrogen-bonding interacti ons. This finding supports the idea that HYP residues may he important for the assembly of the triple helices in the collagen fibrils and may stabiliz e the fibrils by mediating direct contacts between neighboring molecules. ( C) 2001 John Wiley & Sons, Inc.