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8 citations found for Kiyotani,

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Rhoiptelenol, (2), isolated from Ficus thunbergii Maxim. (Moraceae), has been reported as a triterpenoid component. The title compound, (1), whose molecular formula was shown by its high-resolution mass spectrum to be C32H52O2, was obtained from (2) by acetylation with Ac2O and pyridine. The structure of (1) was proved by NMR spectroscopy to be one of a rearranged ursane-type triterpenoid with five six-membered rings. We have described the conformation and geometry of (1) by an X-ray crystallographic analysis and molecular-mechanics calculations.

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Acta Cryst. (2011). A67, C272-C273
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The title compound, (7E)-3[beta],6[beta]-dihydroxy-10-normegastigm-7-en-9-oic acid, (1) [(E)-3-(1,4-dihydroxy-2,2,6-trimethyl-1-cyclohexyl)acrylic acid, C12H20O4], which is a kind of degraded carotenoid, was isolated from the hepatoprotective n-butanol soluble fraction of the methanol extract of Glycosmis arborea. From NMR and other spectral analyses, (1) was inferred to possess a new 10-normegastigmane skeleton and its molecular formula was determined by high-resolution mass spectrometry. We describe herein the conformation of the ring system and configuration of the substituents based on X-ray diffraction analysis. The crystal structure is stabilized by intermolecular O-H...O hydrogen bonds.

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Acta Cryst. (2014). A70, C1463
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We propose muSR experiments on trypsin-BPTI complex to visualize the electron and proton transfer processes occurring in the catalytic reaction of the trypsin. The mechanism of an inhibitory effect of the BPTI is interpreted that the reaction products of BPTI remain at a part of the structure and the reverse reaction reforms the stable trypsin-BPTI complex, which has been confirmed by neutron diffraction experiment of the trypsin-BPTI complex [1]. However, it never sees the real image of the proton and electron transfer processes directly. According to the model provided by the results of neutron diffraction experiments, the proton and electron transfer processes are continuously occurring in a crystal of trypsin-BPTI complex and the process induces the local magnetic field. The slow muon is very adequate because the position, where mu+ is captured, is absolutely negatively charged oxyanion hole close to the reaction center of Trypsin. The distance between the oxyanion hole and the active peptide bond is about 10Å. When the turn over time of the catalytic reactions is assumed to be 10msec or so, the induced magnetic field would be estimated as 0.2 micro-T. In order to check the effectiveness of the measurement of the [mu]SR experiments on trypsin-BPTI complex, another measurement of the muSR experiments on the trypsin- MIP complex is adequate [2]. Here, MIP is a kind of the trypsin inhibitor, which completely stops the catalytic reaction of trypsin. In the trypsin-MIP complex, no electron and proton transfers at all in the active site of trypsin and captured mu+ at the oxyanion hole would never be sensitive to the induced magnetic field [3].

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Crystals of L-leucylglycine (L-Leu–Gly) 0.67-hydrate, C8H16N2O3·0.67H2O, (I), were obtained from an aqueous solution. There are three symmetrically independent dipeptide zwitterionic mol­ecules in (I) and they are parallel to one another. The hydrogen-bond network composed of carboxyl­ate and amino groups and water mol­ecules extends parallel to the ab plane. Hydro­philic regions composed of main chains and hydro­phobic regions composed of the isobutyl groups of the leucyl residues are aligned alternately along the c axis. An imidazolidinone derivative was obtained from L-Leu–Gly and acetone, viz. [(4S)-2,2-dimethyl-4-(2-methyl­prop­yl)-5-oxo­imid­azolidin-3-ium-1-yl]acetate, C11H20N2O3, (II), and was crystallized from a methanol–acetone solution of L-Leu–Gly. The unit-cell parameters coincide with those reported previously for L-Leu–Gly dihydrate revealing that the previously reported values should be assigned to the structure of (II). One of the imidazolidine N atoms is protonated and the ring is nearly planar, except for the protonated N atom. Protonated N atoms and deprotonated carb­oxy groups of neighbouring mol­ecules form hydrogen-bonded chains. The ring carbonyl group is not involved in hydrogen bonding.

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Acta Cryst. (1996). A52, C259
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SENJU, a time-of-flight Laue-type single-crystal neutron diffractometer, was developed at the Materials and Life Science Experimental Facility of the Japan Accelerator Research Complex (J-PARC). Molecular structure analysis of a sub-millimetre taurine crystal and magnetic structure analysis of an MnF2 crystal were performed to evaluate its performance.

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