1.The effect of deuterium oxide on the stability of the collagen model peptides H-(Pro-Pro-Gly)(10)-OH, H-(Gly-Pro-4(R)Hyp)(9)-OH, and Type I collagen.
Mizuno K1, Bächinger HP. Biopolymers. 2010 Jan;93(1):93-101. doi: 10.1002/bip.21305.
The collagen triple helix has a larger accessible surface area per molecular mass than globular proteins, and therefore potentially more water interaction sites. The effect of deuterium oxide on the stability of collagen model peptides and Type I collagen molecules was analyzed by circular dichroism and differential scanning calorimetry. The transition temperatures (T(m)) of the protonated peptide (Pro-Pro-Gly)(10) were 25.4 and 28.7 degrees C in H(2)O and D(2)O, respectively. The increase of the T(m) of (Pro-Pro-Gly)(10) measured calorimetrically at 1.0 degrees C min(-1) in a low pH solution from the protonated to the deuterated solvent was 5.1 degrees C. The increases of the T(m) for (Gly-Pro-4(R)Hyp)(9) and pepsin-extracted Type I collagen were measured as 4.2 and 2.2 degrees C, respectively. These results indicated that the increase in the T(m) in the presence of D(2)O is comparable to that of globular proteins, and much less than reported previously for collagen model peptides [Gough and Bhatnagar, J Biomol Struct Dyn 1999, 17, 481-491].
2.Studies on novel peptidomimetics having bi-directional dispositions of hydroxylated D-Pro-Gly motifs anchored on a C(2)-symmetric iminosugar-based foundation.
Chakraborty TK1, Srinivasu P, Kumar SK, Kunwar AC. J Org Chem. 2002 Apr 5;67(7):2093-100.
A rigid pyrrolidine based scaffold comprising of 2,5-dideoxy-2,5-imino-D-idaric acid (1) is developed. Attachment of peptide strands to the carboxylic groups at both ends of this novel template led to the peptidomimetics 2 and 3. Conformational analysis by NMR studies revealed that compounds 2b, 3b and 2c, 3c take interesting turn structures (C(2) symmetric for 2c and 3c) in DMSO-d(6) consisting of identical intramolecular hydrogen bonds at two ends between LeuNH --> sugar-OH as depicted in structure A, whereas 2a and 3a display structures with regular beta-turns with hydrogen bonds between LeuNH --> Boc-C=O in one-half of their molecular frameworks (structure B), characteristic of the turn structures commonly observed in "D-Pro-Gly"-containing peptides. These results suggest that a cis hydroxyl group at the 3-position of the proline residue favors a pseudo beta-turn-like nine-membered ring structure in hydroxyproline-containing peptides involving an intramolecular hydrogen bond between the hydroxyl and the i + 2 backbone amide.
3.Infinite pleated beta -sheet formed by the beta-hairpin Boc-beta-Phe-beta-Phe-D-Pro-Gly-beta-Phe-beta-Phe-OMe.
Karle I1, Gopi HN, Balaram P. Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5160-4. Epub 2002 Mar 5.
A beta-hairpin conformation and extended beta-pleated sheet assembly have been characterized by single crystal x-ray diffraction for the synthetic peptide t-butoxycarbonyl--beta-Phe-beta-Phe-D-Pro-Gly-beta-Phe-beta-Phe-methyl ester [beta-Phe: (S)-beta(3) homophenylalanine]. The centrally located D-Pro-Gly segment nucleates a chain reversal in a type II' beta-turn conformation. Two intramolecular cross-strand hydrogen bonds stabilize the peptide fold. Intermolecular NH...O[double bond]C hydrogen bonds (two on each side of the hairpin) connect the hairpins into an infinitely extended beta-sheet. The beta-residues cause all C[double bond]O groups to point in the same direction, resulting in a "polar" sheet by the unidirectional alignment of NH...O[double bond]C hydrogen bonds. In contrast, beta-sheets formed by alpha-residues have alternating directions for the hydrogen bonds, thus resulting in an "apolar" sheet. The crystallographic parameters for C(53)H(66)N(6)O(9) x CH(3)OH are: space group P2(1), a = 9.
