title: Crystal structure of a collagen-like polypeptide with repeating sequence Pro-Hyp-Gly at 1.4 A 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 A 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.
authors.affiliation: Centro di Studio di Biocristallografia, CNR, and Dipartimento di Chimica, Universitá degli Studi di Napoli Federico II, Via Mezzocannone 8. I-80134 Napoli, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Berisio
authors.forename: L
authors.initials: L
authors.lastname: Vitagliano
authors.forename: L
authors.initials: L
authors.lastname: Mazzarella
authors.forename: A
authors.initials: A
authors.lastname: Zagari
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins; D003094:Collagen / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D020449:Repetitive Sequences, Amino Acid; D055672:Static Electricity
chemical_list: D002352:Carrier Proteins; D011506:Proteins; C007105:c1q-binding proteins; D003094:Collagen