The crystal structures of the complexes between d (GAAGCTTC) 2 and actinomycin D have been determined in two crystal forms by X-ray diffraction analyses and refined to R-factors of 0.187 (C2 form) and 0.202 (F222 form) at 3.0Å resolution, respectively. In each complex, actinomycin D intercalates between the middle 5'- (GC) -3' base pairs from the minor groove site and forms hydrogen bonds and van der Waals contacts with DNA. A molecular modeling study based on the crystal structures and a spectroscopic study of the complex in solution have indicated that actinomycin D may have an affinity for A-DNA than B-DNA in approaching to DNA.
Flower colors, from red through purple to blue, are mostly from anthocyanins. Although there are many colors, only a few anthocyanins are found. We have succeeded to solve the structure of real anthocyanin and a sugar containing flavonoid, Cd-commelinin, using the Weissenberg camera for macromolecular crystallography with imaging plates at the Photon Factory. The blue flower-color development and the stability of the color can be explained by metal complexation of anthocyanin and intermolecular hydrophobic association. Commelinin is a new type of stoichiometric supramolecule, which consists of low molecular mass components.
Crystal structures of dimeric copper (II) carboxylates have been investigated to reveal the magneto-structural correlations. The coordination geometry around the Cu (II) atoms in the [Cu (RCOO) 2 L] 2 complexes is usually square pyramidal with four oxygen atoms and a monodentate L. Deformation of the coordination geometry toward trigonal bipyramidal (TBP) is observed in certain complexes (R=CCl3, CPh3) . The TBP deformation reduces the antiferromagnetic interactions between the two Cu atoms in the complex. Results of the X-ray studies are summarized.
Porous silicon (hereafter PS) is produced by anodizing a silicon wafer in an HF solution. This paper describes characteristics of PS such as pore-morphology and crystallinity. Pore-morphology and crystallinity depend on anodization conditions as well as doped impurity and electrical resistivity (p) of wafers. When p-type wafers are employed, PS formed on them gives better crystallinity for lower electrical resistivity (p<0.01Ωcm) than for higher resistivity (p>1Ωcm) . The pore size of the former PS is larger than that of the latter. PS formed on n-type wafers (p<1Ωcm) consists of three layers showing different morphology depending on reaction time. Strong visible light seems to be emitted from PS composed of fine silicon crystallites with degraded crystallinity.
Major proteinacious component in the Alzheimer amyloid plaque is β amyloid protein. The amino-acid sequence of this protein is: Asp-Ala-Glu-Phe-Arg-His-Asp-Ser-Gly-Tyr-Glu-Val-His-His-Gln-Lys-Leu-Val-Phe-Phe-Ala-Glu-Asp-Val-Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-Val-Gly-Gly-Val-Val-lle-Ala-Thr. Among the analogues studied the residues 11-28 showed well-oriented cross β fiber pattern where wide angle reflections could be indexed by an orthogonal lattice having unit cell dimensions a=9.44Å, b=6.92Å and c=10.76Å. The intensity maxima on the equator as well as on higher layer lines were sampled by a larger period (63Å), indicating that the β crystallites constitute higher assembly. The structure was modeled as a tube where 5 beta crystallites constitute the wall.
A brief historical outline of utilization of a microgravity environment in space regarding protein crystallization and the results obtained from the space experiments for these 10 years are indicated. Plans for the space experiments using a space station in Japan and other countries are also mentioned.