Kyoyu Sasaki

Weissenberg camera for macromolecules with imaging plate data collection system at the Photon Factory: Present status and future plan (invited)

A Weissenberg camera for macromolecules with imaging plate data collection system at BL6A and BL18B stations in the Photon Factory is introduced and evaluated. The special feature of these systems is considered matching for both SR‐x rays and protein crystallography. This system is user‐friendly and can collect a large amount of data to higher resolution from the crystal with large unit cell dimensions. A newly developed camera can be used as a time‐resolved Laue camera and a Weissenberg camera. A large image reader (IPR4080) that can scan 400×400 mm2 and 400×800 mm2 sizes of imaging plates has been developed and evaluated. The new data collection system combined with the new camera and IPR4080 will be installed at the BL18B station in October 1994.

Distributions of C2 and C3 radical densities in laser-ablation carbon plumes measured by laser-induced fluorescence imaging spectroscopy

We measured temporal variations of the distributions of C2 and C3 radical densities in carbon plumes produced by laser ablation of graphite in ambient He gas. Laser-induced fluorescence imaging spectroscopy was used for the measurement. The temporal variations of total numbers of C2 and C3 contained in plumes were evaluated by integrating the density distributions. The experimental observations have shown that the gas-phase production of C2 is comparable to the direct production from the target, while C3 is mainly produced in gas phase by three-body reactions between C and C2. In addition, we have discussed a scenario for the temporal evolution of heavy clusters (Cn with n⩾4). The present results are useful for understanding initial formation processes of carbon clusters in laser-ablation plumes.

Isolation and structure of trichotomine and trichotomine G1

Abstract The new pigments, trichotomine ( 1 ) and trichotomine G 1 ( 12 ), which have a novel carbon skelton, have been isolated from the fruits of the plant Clerodendron trichotomum Thunb. On the basis of physical and chemical evidence, the structure of trichotomine ( 1 ) 1,2 was elucidated as an oxidative dimeric compound of 3 - oxo - 2,3 - 5,6 - tetrahydro - 11 H indolizino[8,7-b]indole 5-carboxylic acid and its stereostructure containing the absolute configuration was further determined by means of an x-ray crystallographic analysis. 3 The structure of trichotomine G 1 ( 12 ), a N-β-D-glucopyranosyl trichotomine, is also based on spectral and chemical evidence. A N-β-D-glucopyranosyl indole derivative such as ( 12 ) is the first naturally occurring example. 4

Structure of the yellow-green fluorescent peptide produced by iron-deficient Azotobacter vinelandii strain O

Abstract The yellow-green fluorescent peptide (hereafter called Compound A-1) has been isolated from iron-deficient Azotobacter vinelandii strain O, and the total structure of compound A-1 was determined by X-ray analysis (chromophore moiety) and the subtractive Edman degradation (peptide moiety).

Dynamics of laser-ablation Ti plasmas studied by laser-induced fluorescence imaging spectroscopy

The distributions of Ti+ and Ti densities in laser-ablation Ti plasmas were visualized by laser-induced fluorescence imaging spectroscopy. The absolute Ti density was determined by ultraviolet absorption spectroscopy. The absolute Ti+ density was evaluated by comparing the laser-induced fluorescence intensity from Ti+ with that from Ti. In addition, we evaluated the total numbers of Ti+ and Ti in plasmas by integrating the density distributions spatially. As a result, it was found that the total number of Ti+ was higher than that of Ti in the initial stage of laser-ablation plasmas. In ambient He gas, we observed the temporal increase in the total number of Ti, indicating the gas-phase production of Ti due to neutralization of Ti+. The increase in the total number of Ti+ was also observed, suggesting the production of Ti+ due to neutralization of Ti2+. The present experimental results show that Ti+ and Ti2+ are major species produced by laser ablation of a metal Ti target.

Molecular structure of bacterial endotoxin (Escherichia coli Re lipopolysaccharide): implications for formation of a novel heterogeneous lattice structure

Analyses of crystals of Escherichia coli Re lipopolysaccharide (LPS) formed after storage in 1% triethylamine indicate that the LPS molecules are assembled to form a monolayered structure consisting of a novel heterogeneous lattice structure, the greater part of which is occupied by one kind of lattice (lattice I), corresponding to the acyl chain portion of lipid A, and the remainder is occupied by the other kind of lattice (lattice II), corresponding to the 3‐deoxy‐dmanno‐octulosonic acid (dOclA) dimer and the N‐acetylglucosamine disaccharide of lipid A. X‐ray diffraction reveals that the type of cell is monoclinic (a = 5.53 Å, b = 27.2 Å, c = 6.47 Å , α = 90°, β = 125.8°, γ = 90°). Atomic force microscopy shows that crystals consist of multiple layers; the thickness of a layer corresponds to the b‐axis value, and two types of surface topographies are visualized. One, regarded as the view onto the acyl chain ends, is two‐dimensional arrays of oval bodies that constitute the lattice, with the lattice constants corresponding to the a‐ and c‐axes and the angle of β (lattice I). The other, regarded as the view onto the dOclA dimers, is two‐dimensional arrays of dromedary‐back‐like bodies that constitute the lattice with axes of 9.0 and 10.7 Å and the angle of 65° formed by both axes (lattice II). Based on these results, we present the molecular model of E. coli Re LPS.

Crystallization of Synthetic Escherichia coli-Type Lipid A

Synthetic Escherichia coli‐type lipid A formed hexagonal plate crystals when it was precipitated by the addition of 2 volumes of 95% ethanol containing 375 mM MgCl2 and incubated in 70% ethanol containing 250 mM MgCl2 at 4 C for 10 days. Analyses of crystals by electron diffraction and synchrotron X‐ray diffraction showed that crystals consist of hexagonal lattices with the lattice constant (a side of the lozenge as a unit cell on the basal plane) of 4.62 Å and the longitudinal axis (perpendicular to the basal plane) of 49.3 ±1.3 Å. Results suggest that the previous finding that various kinds of R‐form lipopolysaccharides crystallized but free lipid A isolated by acid hydrolysis from Re lipopolysaccharide did not crystallize under the same experimental conditions (Kato et al, J. Bacteriol., 172: 1516‐1528, 1990) is due to structural changes of lipid A occurring during the procedure of isolation of free lipid A.

The structure of polygonaquinone

Abstract Polygonaquinone, obtained from the roots of Polygonatum species, is shown to have structure D.

Crystallization and analyses of crystals of various chemotypes of R-form lipopolysaccharides from Salmonella spp.

Various chemotypes (Re, Rd2, Rd1P–, Rd1, RcP–, Rc, Rb3, Rb2, Rb1, and Ra) of R‐form lipopolysaccharides (LPSs) of Salmonella spp. were crystallized by treatment with 70% ethanol containing 250 mM MgCl2, and crystals of the LPSs were observed electron microscopically and analyzed by electron diffraction and synchrotron X‐ray diffraction. All the LPSs tested formed three‐dimensional crystals showing very similar shapes; hexagonal plate, solid column, discoid, square or rectangular plate, lozenge plate and truncated hexangular or rectangular pyramid forms. Electron diffraction patterns from the hexagonal plate crystals of all these LPSs obtained by electron irradiation from the direction perpendicular to the basal plane showed that they consist of hexagonal lattices with the lattice constant of 4.62 Å. The crystals of all the LPSs thus formed gave ring‐like X‐ray diffraction patterns because of their small sizes. The long‐axis values were calculated from the X‐ray diffraction patterns from crystals of all the LPSs in the low‐angle region and they corresponded roughly to the length of the proposed primary chemical structures of the R cores of the LPSs. The volume occupied by a single molecule of all the LPSs were calculated from the molecular weights based on the proposed structures and the crystallographic data obtained by electron diffraction, X‐ray diffraction, and density determination.

X-ray studies of water structure in 2 Zn insulin crystal

The water structure of rhombohedral 2 Zn insulin crystal which contains about 280 water molecules and 0.55-0.60 mol citrate molecules per dimer has been studied by X-ray crystallographic refinement with 1.1 A resolution data. Atomic parameters of 83 fully occupied and 258 partially occupied water molecules and 0.3 mol of citrate were obtained. Full matrix least-squares method with isotropic temperature factor was used for the refinement of partially occupied water molecules. The water molecules in this crystal exist in one of the three states: fully occupied water, partially occupied water and water continuum, and a schematic model of water structure in protein crystal was proposed. The flexibility of water molecules is described.