A possible non-invasive method of microscopic imaging of X-ray sources included in the brain is described. The principle is basically similar to the Fourier-Transform-Telescope developed for imaging celestial X-ray sources.
Detailed swath mapping of topography associated with other geophysical measurements has indicated that the outer wall of the western Kuril Trench is dissected by a number of normal faults which are parallel to the linear magnetic anomalies in the northwestern margin of the Pacific Ocean but slightly oblique to trend of the axis of the Kuril Trench by roughly 10°. It is inferred that about 130 million years old tectonic fabrics in the oceanic crust are rejuvenated when the lithosphere is bent downward under extensional stress at the trench outer wall to be subducted beneath the landward wedge. This pattern of faults shows a sharp contrast to alignment of faulted scarps found in the outer wall of the Japan and Izu-Ogasawara Trenches both trending by 60° oblique to the magnetic lineations. Majorities of outer wall scarps there are parallel to the trench axis, whereas some scarps trend subparallel to the axis forming zigzag pattern of escarpment. As direction of the extensional stress caused by downward bending of the lithosphere in these trench walls is nearly perpendicular to the old tectonic stresses, normal faultings seem to occur under the influence of the ongoing stress distribution alone irrespective of their old history.
The behavior of rare earth elements (REE) in interaction between water and basalt was investigated on different conditions. The W-type tetrad effect was observed for water under gentle environment at room temperature. The REE pattern, having tetrad effect and negative Ce anomaly, is similar to that of seawater. On the other hand, the REE patterns of waters resulting from violent environment, i.e., at high temperature (70°C) or under operation of supersonic waves, show smooth curve with little if any tetrad effect, rather resembling that of source basalt. It is noted that the tetrad effect often observed in natural waters also appears in simple interaction in situ between pure distilled water and basalt. This results would throw light on understanding of tetrad effects observed in natural waters.
Self-assembly of hydrophobized polysaccharides in water was investigated by dynamic and static light scatterings, and by fluorescence and circular dichroism spectroscopies. Cholesterol-bearing pullulan (CHP) forms nanosize hydrogel by self-aggregation in water. The hydrogel network was formed by non-covalent cross-linked domain. The nanoparticles strongly bound various hydrophobic compounds. Induced circular dichroism was observed upon the enantioselective binding with bilirubin.
Natural methyl tuberonate 6b, jasmine ketolactone 3 and its epimer 4 were synthesized from the intermediate 7 in almost optically pure form (over 99% e.e.). Jasmonoids are now interesting for their various activities to the plants, so our synthetic samples must be useful for their further biological study.
We have reported a dumbbell-shaped structure of dystrophin molecule (Murayama etal., 1990; Sato et al., 1992). However its small population has raised a possibility that the dumbbell structure was due to a contaminant protein, such as type VI collagen of aorta origin. In the present study, type VI collagen was purified from bacterial collagenase-treated aorta of the rabbit. Its rotary shadowed images were very similar to those present in the dystrophin preparations. However, the antiserum to type VI collagen raised in a mouse did not react with dystrophin samples. A tentative explanation for the small population of the dumbbell structure is described.
DNA recognition by Myb and that by LexA are compared in the light of their solution structures. The two proteins bind to DNA using the same type of structural units and discriminate between DNA sequences through the same type of recognition helices therein.
The three-dimensional structure of an enzyme, 2, 3-dihydroxybiphenyl dioxygenase, from Pseudomonas sp. strain KKS102 has been solved by X-ray crystal structure analysis. The enzyme conventionally called “BphC” is an important member in the biodegradation pathway for PCBs (polychlorinated biphenyls) which are the widely distributed environmental pollutants. The BphC enzyme is an oligomeric enzyme made up of eight identical subunits of 292 amino acid residues. Each subunit consists of two domains: Domain 1(residues 1 to 135) and Domain 2 (resiuues 136 to 292). Each domain consists of two repetitions of a unique folding motif each consisting of ca. 55 amino acid residues. The unique motif may be classified into an α-β sandwich structure having a “βαβββ” type topology. In the active site of each subunit, one Fe ion surrounded by five ligands roughly arranged in a trigonal bipyramidal geometry was found.
DNA recognition of zipperless basic-zipper (bZip) proteins and zipped homeodomains (HDs) are discussed in the light of the structure and the DNA-binding specificity of ordinary bZip and HD proteins. Proteins, Mastermind, Skin-1 and Srg-1, have twelve residue sequences which are very similar to that of the basic domain but lack the “zipper” sequences, which follows the basic domain in bZip proteins. It is predicted here that these proteins and Zeste and RAP1 have a domain which is composed of three α-helices as in an HD and the proteins bind to the DNA by a recognition helix of the HD-bZip type.
An attempt is made to identify the functional sites on a primary sequence of trypsin. The process of identification is based on two hypotheses: 1) The regional variance of an amino acid sequence correlates with its function. 2) A functional site lies near the surface of a protein. From the first hypothesis, possible functional sites in a protein are defined. By the second hypothesis, a functional site near the surface is defined as an exposed functional site. Further specification of functional sites is made from a consideration on an issue “how a functional system is constructed from a couple of functional sites.” It is found that the active sites of trypsin that are already known by biochemical experiments are located near or in the functional sites derived from the estimation.
Functional sites of F-protein of Newcastle disease virus (NDV-F) are determined by the DEV analysis. It includes 91-R that is already known by experiment to be the cleavage site. Interaction of trypsin and its substrate, NDV-F, is then investigated by two mechanisms: two- or mono-molecular interactions. By the two-molecular mechanism, a functional site other than the region containing active sites of trypsin, or a cleavage site of NDV-F interacts as the initial step. By mono-molecular mechanism, a possible interacted complex is visualized between functional sites of trypsin and a cleavage site of NDV-F. In addition, some region that connects functional sites (connector) is found to be important to make complex. Several model complexes are made and analyzed. Results suggest the fluctuated nature of interaction. The interaction between the 84-D region of trypsin and the hydrophobic amino acid sequence in NDV-F, which is always observed from the beginning, is considered to be the key process in the trypsin catalysis.
It has been shown that norharman and harman, present in our environment, may act as genotoxic compounds in human body. In order to have an insight of the extents of exposure to these β-carbolines, we measured their levels in human urine. Samples of 24-hr urine were collected from ten healthy volunteers eating a normal diet and three patients receiving parenteral alimentation. The urine samples were separated by blue cotton treatment, cation exchange IONEX column chromatography and HPLC on a semi-preparative ODS column. The contents of norharman and harman in the partially purified materials were determined by HPLC with a fluorometric detector. Norharman and harman were detected in all 24-hr urine samples from healthy volunteers at levels of 9.3-33.5ng and 97.7-298ng, respectively. These β-carbolines were also found to be present in the urine of the three patients and their levels in the 24-hr urine were comparatively lower than those in urine of healthy volunteers eating normal diet. After changing from parenteral alimentation to diet, the two β-carboline levels in urine increased in two of the three patients. From the above results, it is suggested that humans are continuously exposed to norharman and harman derived endogenously and exogenously.