Structural highlights
Publication Abstract from PubMedThe single-crystal structure of the collagen-like peptide (Pro-Pro-Gly)4 -Hyp-Asp-Gly-(Pro-Pro-Gly)4 , was analyzed at 1.02 A resolution. The overall average helical twist (theta = 49.6 degrees ) suggests that this peptide adopts a 7/2 triple-helical structure and that its conformation is very similar to that of (Gly-Pro-Hyp)9 , which has the typical repeating sequence in collagen. High-resolution studies on other collagen-like peptides have shown that imino acid-rich sequences preferentially adopt a 7/2 triple-helical structure (theta = 51.4 degrees ), whereas imino acid-lean sequences adopt relaxed conformations (theta < 51.4 degrees ). The guest Gly-Hyp-Asp sequence in the present peptide, however, has a large helical twist (theta = 61.1 degrees ), whereas that of the host Pro-Pro-Gly sequence is small (theta = 46.7 degrees ), indicating that the relationship between the helical conformation and the amino acid sequence of such peptides is complex. In the present structure, a strong intermolecular hydrogen bond between two Asp residues on the A and B strands might induce the large helical twist of the guest sequence; this is compensated by a reduced helical twist in the host, so that an overall 7/2-helical symmetry is maintained. The Asp residue in the C strand might interact electrostatically with the N-terminus of an adjacent molecule, causing axial displacement, reminiscent of the D-staggered structure in fibrous collagens. (c) 2013 Wiley Periodicals, Inc. Biopolymers 99: 436-447, 2013. Crystal structure of the collagen model peptide (Pro-Pro-Gly)4 -Hyp-Asp-Gly-(Pro-Pro-Gly)4 at 1.0 A resolution.,Okuyama K, Kawaguchi T, Shimura M, Noguchi K, Mizuno K, Bachinger HP Biopolymers. 2013 Jul;99(7):436-47. doi: 10.1002/bip.22198. PMID:23616212[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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