Preparation and characterization of imogolite/DNA hybrid hydrogels.

Imogolite is one of the clay minerals contained in volcanic ash soils. The novel hybrid hydrogels were prepared from imogolite nanofibers and DNA by utilizing strong interaction between the aluminol groups on imogolite surface and phosphate groups of DNA. The hybrid hydrogels of imogolite and DNA were prepared in various feed ratios, and their physicochemical properties and molecular aggregation states were investigated in both dispersion and gel states.

Helical twists of collagen model peptides.

Average helical twists were calculated by the method of Sugeta and Miyazawa (Biopolymers 1967, 5, 673-679) for all of the collagen model peptides analyzed to date. Calculation of the helical twists of all triplets in each peptide strand provided novel insights for several model peptides. In the (Pro-Pro-Gly)n (n = 9 and 10), the helical twists showed cyclic fluctuations between 40 and 65 degrees with a 20 A period, suggesting that their molecular conformations were close enough to the ideal 7/2-helix to show the helical repeat of 20 A.

Conformation of alloHyp in the Y position in the host-guest peptide with the pro-pro-gly sequence: implication of the destabilization of (Pro-alloHyp-Gly)10.

The crystal structure of the host-guest peptide, (Pro-Pro-Gly)4-(Pro-alloHyp-Gly)-(Pro-Pro-Gly)4, was analyzed at high resolution. allohydroxyproline (alloHyp), 4S-hydroxyproline, was successfully characterized through the use of a host-guest peptide, while the previous study indicated the inability of a triple helical formation of (Pro-alloHyp-Gly)10. A detailed analysis of alloHyp conformation in collagen-like models sheds light on the role played by its puckering in the triple-helix stabilization and destabilization.