bluuebunny/crossref_metadata_2025_split huggingface dataset:
Discrimination of Doxylpalmitic Acids by γ-Cyclodextrin: ESR Study of Stability, Conformation, and Dynamics
Authors: Tanaka Hisao , Kato Naoko , Kawazura Hiroshi 
Published: June 2006

Abstract
Six palmitic acids labeled at different methylene positions by paramagnetic doxyl moiety were used as guests in order to examine molecular discrimination using γ-cyclodextrin (γ-CD). The DPA inclusion complexes using γ-CD in an aqueous solution were characterized according to stability, conformation, and dynamics at 25 °C, mainly based on ESR spectral analyses and supported by force-field calculations. The stability was equal among all DPA complexes, as represented by the formation constant Ks = 8.0(±0.5) × 102 M−1 (M = mol dm−3), corresponding to the conformation constant when the palmitate chain penetrates a CD cavity and the doxyl ring locates inside the cavity. Both overall molecular motion and chain segmental motion of DPA, represented by the parallel (Rzz) and perpendicular components (Rxx = Ryy) of the rotational diffusion tensor, respectively, were significantly restricted in inclusion state. The magnitude of restriction of segmental motion increased towards the chain terminals from the center, indicating that faster segmental motion was restricted at a higher rate. Thus, a series of DPAs were discriminated by γ-CD in terms of chain segmental motion but not in terms of stability, to present a typical example of dynamic molecular discrimination.
Semiempirical (AM1) Studies of Possible and Preferred Site(s) of Porotnation in the Gas Phase for Polyfunctional Nitrogen Bases: N1,N1-Dimethyl-N2-azinylformamidines
Authors: Raczynska Ewa D , Taft Robert W 
Published: June 2006

Abstract
Proton affinities for seven polyfunctional nitrogen bases (N1,N1-dimethyl-N2-azinylformamidines) containing one amidine moiety and one, two or three nitrogen atoms in ortho-, meta-, and/or para-positions of the heterocyclic six-membered group have been predicted by semiempirical AM1 method. The preferred site(s) of protonation and exceptionally high gas-phase basicity of N1,N1-dimethyl-N2-azinylformamidines containing 2-azinyl group antiperiplanar to the functional carbon atom in the amidine moiety have been discussed. The effects of one group on the basicity of the other one have been compared with those found for the corresponding model amidines and azines.
Superdelocalizabilities of Linear Chains
Authors: Isihara Makoto 
Published: June 2006

Abstract
This paper analyzes superdelocalizabilities (SDs) of even-membered linear chains in a simple noncomputational way. Two basic relationships connecting SDs to bond orders are prepared in general form and applied to linear chains to provide a plain analytic expression to SDs. Behaviors of SDs in long linear chains are examined by using this analytic expression. Simple estimation formulas are derived for SDs near the end and in the middle of a long linear chain and the distinctive reactivity of end sites is fully verified. Comparisons with behaviors of frontier electron densities and frontier SDs manifest that these approximate indices cannot substitute for SDs in long linear chains.
Synthesis and Optical Properties of Transparent LiAl5O8 : Co2+ Films by the Sol–Gel Method
Authors: Ishihara Tsuguo , Tanaka Katsuhisa , Hirao Kazuyuki , Soga Naohiro 
Published: June 2006

Abstract
A transparent LiAl5O8 : Co2+ film was prepared by the sol–gel method using LiNO3, Al(i-OC3H7)3, and Co(NO3)2·6H2O. The microstructure and optical properties of the film were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical absorption, and fluorescence measurements. The XRD analysis indicated that a (110)-oriented LiAl5O8 film is formed when the gel film is heat-treated at 773 K. The XRD patterns of LiAl5O8 films heat-treated above 1173 K manifest diffraction lines assigned to reflections from the (110), (220), and (440) planes. In contrast, only the diffraction lines corresponding to the (220) and (440) planes were observed in a LiAl5O8 film heat-treated below 1073 K. These results suggest that LiAl5O8 films heat-treated below 1073 K and above 1173 K possess disordered and ordered structures, respectively. The LiAl5O8 : Co2+ films obtained by a heat treatment below 1173 K, which contain crystallites of less than 10 nm, are optically transparent. The optical absorption spectra at room temperature indicate that the absorption band due to the 4A2 → 4T1(P) transition of Co2+ ions in tetrahedral sites showed three peaks (540, 580, and 625 nm). The fluorescence spectra of the films obtained by a heat treatment above 1173 K manifest a sharp line at around 658 nm with vibronic sidebands in the long-wavelength region. The emission bands are ascribed to transition from 4T1(P) to 4A2 of Co2+ ions in tetrahedral sites in the ordered phase.
Determination of Lead(II) by Electrothermal Atomization Atomic Absorption Spectrometry after Coprecipitation with Gallium(III) Phosphate
Authors: Kagaya Shigehiro , Ueda Joichi 
Published: June 2006

Abstract
Gallium(III) phosphate coprecipitates quantitatively 0.1—2.0 μg of lead(II) from 100—500 cm3 of a sample solution at pH 2.5—6.0. The coprecipitated lead(II) can be sensitively determined by electrothermal atomization atomic absorption spectrometry without any influence of gallium(III) phosphate. The calibration curve is linear from 4 to 80 ng cm−3 for lead(II). The detection limit (signal/noise = 2) is 0.095 ng cm−3 of lead(II) in 500 cm3 of the initial sample solution. Thirty-four diverse ions tested did not interfere seriously with the determination of lead(II). This method was successfully applied to the determination of lead(II) in tap and river water.
Formation of 3-Methylene-1,4-cyclohexadienes from α,α,α′,α′-Tetraaryl-1,4-benzenedimethanols by the Intramolecular Migration of an Aryl Group
Authors: Wada Masanori , Wei Wen-hao , Kirishima Katsuhiko , Natsume Satoko , Erabi Tatsuo 
Published: June 2006

Abstract
By reactions of diethyl p-phthalate with 2,6-dimethoxyphenyllithium, ΦLi, a tri-substituted compound, p-HOCΦ2C6H4C(O)Φ (1), or tetra-substituted 1,4-benzenedimethanol, p-HOCΦ2C6H4CΦ2OH (2a), were obtained. Compound 1 further reacted with aryllithium, ArLi, to give the 1,4-benzenedimethanols, p-HOCΦ2C6H4CArΦOH (Ar = 4-MeC6H42b, 4-MeOC6H42c). When 2a was treated with acid in dimethyl sulfoxide, 3-(2,6-dimethoxybenzoyl)-3-(2,6-dimethoxyphenyl)-6-[bis(2,6-dimethoxyphenyl)methylene]-1,4-cyclohexadiene, (4a) was obtained in quantitative yield under a variety of conditions. The reaction is understood to involve an initial formation of carbenium ion, [p-Φ2C+–C6H4CΦ2OH] (3a), of which the positive charge must be partly shared with the other end of the p-phenylene ring, where one of the neighboring Φ-groups migrates. Reactions in acetone resulted to give 4a or dark-violet crystals of (2′,6′-dimethoxy-4-biphenylyl)bis(2,6-dimethoxyphenyl)carbenium perchlorate, [(4-ΦC6H4)CΦ2]ClO4, depending on the reaction conditions. Reactions in methanol, ethanol, or in hot 2-propanol resulted to give the reduced compound, (4-ΦC6H4)Φ2CH. The 1,4-benzenedimethanols, 2b and 2c, also reacted with perchloric acid in dimethyl sulfoxide to form the 3-methylene-1,4-cyclohexadiene derivatives, (Ar = 4-MeC6H44b, 4-MeOC6H44c), respectively. Evidence is given by the 1H NMR spectrum, which shows the formation of intermediate carbenium ions 3a—c.
Scandium(III) Perfluorooctanesulfonate [Sc(OPf)3] : A Novel Catalyst for the Hetero Diels–Alder Reaction of Aldehydes with Non-Activated Dienes
Authors: Hanamoto Takeshi , Sugimoto Yuichi , Jin Yong Zhi , Inanaga Junji 
Published: June 2006

Abstract
Scandium(III) perfluorooctanesulfonate [scandium(III) perflate, Sc(OPf)3] was prepared from either scandium(III) chloride or oxide and perfluorooctanesulfonic acid. The perflate thus obtained acts as a novel Lewis acid catalyst for the intermolecular hetero Diels–Alder reaction of aldehydes with non-activated dienes under mild conditions. The characteristic features of the catalyst include (i) low hygroscopicity, (ii) ease of handling, and (iii) robustness for the recycling use.
Dehydrooligopeptides. XX. Unusual Peptide Bond Cleavage of Dehydrotripeptide Esters Containing α-Dehydroamino Acid Residue at P2 by Using Papain
Authors: Shin Chung-gi , Arai Kazushige , Hotta Keitaro , Kakusho Takeshi 
Published: June 2006

Abstract
Enzymatic ester hydrolysis and coupling of various N-protected Δ2-dehydrotripeptide methyl esters (Boc–AA–ΔAA–AA–OMe) (4) by using protease papain in McIlvaine buffer are mainly described. The substrates (4) used were prepared by one-pot coupling of N-carboxy-α-dehydroamino acid anhydride (ΔAA·NCA) with N- and C-component l-α-amino acids (AA). Even in the enzymatic reaction of 4 containing an unusual ΔAA residue, the normal ester hydrolysis took place to give Boc–AA–ΔAA–AA–OH (6) and, in certain cases, the interesting unusual peptide bond cleavage at P2 of 6 occured further to give the unexpected N-(1,2-dioxoalkyl)–AA–OH. Besides examining in detail the differences between the enzymatic actions to the structures of 4, we also studied the mechanisms of the ester and peptide bond hydrolyses. As the results, the reverse enzymatic coupling of 4 with H–AA–ΔVal–OMe was first achieved to give dehydropentapeptide containing two ΔAA residues.
Enzymatic Preparation of (S)-3-Hydroxytetradecanoic Acid and Synthesis of Unnatural Analogues of Lipid A Containing the (S)-Acid
Authors: Liu Wen-Chi , Oikawa Masato , Fukase Koichi , Suda Yasuo , Winarno Hendig , Mori Saeko , Hashimoto Masahito , Kusumoto Shoichi 
Published: June 2006

Abstract
Synthesis of unnatural analogues, that contain (S)-3-hydroxytetradecanoyl moieties in place of the corresponding natural (R)-isomers, of both lipid A and its biosynthetic precursor, designated precursor Ia or lipid IVA, has been achieved through our recently developed procedure. (S)-3-Hydroxytetradecanoic acid was prepared from its racemate through the optical resolution by the use of a lipase and subsequent fractional recrystallization. The (S)-acyl analogue of lipid A exhibited slightly stronger interleukin-6 inducing activity than the corresponding natural lipid A, and the (S)-acyl analogue of the biosynthetic precursor was far more active than the natural precursor in inhibiting the induction of interleukin-6 by lipopolysaccharide.
Effects of High-Pressure on the Activity and Spectroscopic Properties of Carboxypeptidase Y
Authors: Kunugi Shigeru , Yanagi Yuuichi , Kitayaki Moto , Tanaka Naoki , Uehara-Kunugi Yukiko 
Published: June 2006

Abstract
The effects of high pressure, up to 400 MPa, on the catalytic activity and the fluorescence and CD of carboxypeptidase Y (CPDY) were investigated.
CPDY showed a pH-dependent Suc–Ala–Ala–Pro–Phe–pNA hydrolysis similar to other neutral substrates. The apparent second-order rate showed a gradual decrease with increasing pressure, which was related to an increase in Km and a decrease in kcat.
The intrinsic fluorescence of CPDY showed a gradual decrease in the intensity and a red shift in the maximum wavelength with pressure. The transition curve did not follow a simple tow-state transition, but contained at least three states. The first transition occurred at around 100 MPa and the second one occurred at pressures higher than 200 MPa. After incubation at 300 MPa, both the peak intensity and the maximum wavelength did not show complete restoration; the pressure-induced change is substantially irreversible.
The latter change corresponds to the increased binding of a fluorescent hydrophobic probe molecule (8-anilino-1-naphthalenesulfonic acid) to this protein; however, the CD spectrum showed practically no evidence of irreversible changes in the protein’s secondary structure.
Bioactive Compounds from the Sea Hares of Two Genera: Aplysia and Dolabella
Authors: Yamada Kiyoyuki , Kigoshi Hideo 
Published: June 2006

Abstract
This account describes the chemistry of the bioactive compounds isolated from the sea hares belonging to two genera: Aplysia and Dolabella. The bioactive compounds are classified as i) polyketides, ii) terpenes, iii) peptides and depsipeptides, and iv) others. Special emphasis is placed on the chemistry of cytotoxic compounds such as aplyronines and dolastatins that were obtained in our laboratory: Their isolation, structural elucidation, synthesis, and selected bioactivities data are summarized.
Oscillations of Membrane Current or Membrane Potential and Voltammetric Elucidation of Their Mechanisms
Authors: Maeda Kohji , Hyogo Wataru , Nagami Shuzo , Kihara Sorin 
Published: June 2006

Abstract
Novel oscillations of membrane current or membrane potential were observed when the transfer of Na+ from one aqueous solution (W1) containing 0.1 M NaCl to another (W2) in the absence of Na+ through a liquid membrane (LM) containing dilute Na+ was forced by an applied membrane potential or membrane current, respectively. The current oscillation was induced by the addition of acetylcholine in W1, and inhibited by the addition of such hydrophobic ions as tetraalkylammonium ions or glutamate ion in W1. These oscillations were similar to those at biomembranes with so-called “sodium channels” as regards both induction and inhibition, though the liquid membrane system did not contain any channel proteins. The current and potential oscillations were also inhibited by the addition of bovine serum albumin in W2. The mechanisms of the oscillations, the induction and the inhibitions were elucidated by referring to voltammograms for the ion transfer through a membrane as well as those at aqueous/membrane interfaces, and by taking into account the adsorption of Na+ at the LM/W2 interface. Various LM systems which exhibit the oscillations accompanied by transports of ions other than Na+ were also investigated, and the general feature of the oscillations of membrane current or potential is discussed.
Three-Dimensional Structural Feature Search of Proteins
Authors: Kato Hiroaki , Takahashi Yoshimasa 
Published: June 2006

Abstract
This paper describes a three-dimensional (3D) structural feature search, or motif search, of proteins using SS3D-P. Our present approach is based upon the use of a substructure searching program for small organic molecules, SS3D, reported in our previous work. In SS3D-P, the 3D structure of a protein is approximated with the coordinates of α-carbon atoms of the main chain, and treated as a molecular graph that is represented using a distance matrix. The program allows us to specify the tolerance value of the inter-residual distances to be compared. Several characterization schemes are also available for the different amino acid residues that can be distinguished. The program we have developed was validated by search trials with 3D query patterns of known protein motif structures: the P-loop, the EF-hand, and the Zinc finger motif using Protein Data Bank (PDB) structure files.
The Surface Heterogeneity of Supported Platinum Catalysts as Studied by the Interrupted Temperature-Programmed Desorption of Carbon Monoxide
Authors: Arai Masahiko , Fukushima Makane , Nishiyama Yoshiyuki 
Published: June 2006

Abstract
The interrupted temperature-programmed desorption of carbon monoxide was used to characterize the surface heterogeneity of supported platinum catalysts. The surface of platinum particles is divided into two different groups of desorption sites. For one group, the surface diffusion of carbon monoxide takes place easily, and it desorbs at low temperatures. For the other, the desorption of carbon monoxide requires higher temperatures, and surface diffusion does not occur. For the latter group, the distribution of the activation energy of desorption is determined by a method that the authors have recently developed (Appl. Surf. Sci., 89, 11 (1995)).
Photocatalyzed Decomposition of 4-Chlorophenol by Keggin-Type Heteropolytungstate
Authors: Einaga Hisahiro , Misono Makoto 
Published: June 2006

Abstract
The photocatalytic decomposition of 4-chlorophenol with a Keggin-type heteropolytungstate, PW12O403− (abbreviated as PW123−), under aerated conditions has been investigated in an aqueous or water-acetonitrile solution by using a 300 W Xe arc lamp at 303 K. The kinetics of the reaction indicated that the reaction proceeds via a Langmuir–Hinshelwood (or Michaelis–Menten) type mechanism, in which the complexation between the heteropolyanion and 4-chlorophenol exists as a pre-equilibrium step. This complex formation was evidenced by the observation of a new band at λ &lt; 650 nm and the enhancement of the solubility of 4-chlorophenol in water in the presence of PW123−. The intensity of the new band varied in parallel with the reaction rate, depending on the concentrations of 4-chlorophenol and acetonitrile. This fact was consistent with the mechanism proposed.
Effect of Mastoparan on the Binding of Ca2+ to S-100 Proteins in the Presence of Zn2+
Authors: Matsuda Sadayuki 
Published: June 2006

Abstract
S-100 proteins, which are acidic Ca2+-binding proteins, exist in the brain and modulate enzymes and proteins as does calmodulin. In order to clarify some unique characteristics of S-100 proteins, the effects of mastoparan (MP) on the Ca2+ affinity of two S-100 protein isoforms (S-100a.a′, S-100b) in the presence of Zn2+ were examined using dialysis and stopped-flow methods. It was clearly demonstrated that the enhancement of S-100a.a′ was distinct from that of S-100b. Although the former isoform was affected only by the addition of MP, the latter was affected by MP or Zn2+.
The Inhibitory Capability of Decorative Plated Coatings for the Growth of Bacteria
Authors: Zhao Zhi-hong , Hasebe Kazuyuki , Sakagami Yoshikazu , Osaka Tetsuya 
Published: June 2006

Abstract
The antibacterial activity of various electroplated coatings (cobalt, zinc, copper, and cobalt-containing alloys of nickel, zinc, chromium) was determined by a “Drop-method” antibacterial experiment against pathogenic bacteria (gram-positive bacterial S. aureus, MRSA, and gram-negative bacteria E. coli, P. aeruginosa). It was found that all of them possessed a higher antibacterial activity than stainless steel. The ralationship between the inhibitory capability for the growth of bacteria and the rest potential of the electroplated coatings was also investigated. A significant antibacterial activity of the coatings was apparently displayed by a rest-potential shift to more negative values. It was suggested that all of the tested bacteria fell closely within the lethal range when the rest potentials were lower than -543 mV. However, some amount of metal ions dissolved from various from various electroplated coatings was measured; accordingly, the inhibitory capability of the simulated dissolution concentrations of metal ions the growth of bacteria is discussed.
Stereochemical Control in Microbial Reduction. XXIX. Mechanism of Stereochemical Control with an Additive in the Diastereoselective Reduction by Geotrichum candidum
Authors: Kawai Yasushi , Takanobe Kousuke , Ohno Atsuyoshi 
Published: June 2006

Abstract
The reduction of ethyl 2-methyl-3-oxobutanoate with Geotrichum candidum yields approximately equal amounts of the corresponding syn-(2R,3S)- and anti-(2S,3S)-3-hydroxy esters. When the microbe is incubated with methyl vinyl ketone (MVK) or chloroacetone before it is subjected to the reduction, the corresponding anti-(2S,3S)-hydroxy ester is obtained with exclusive enantio- as well as diastereoselectivity. In order to obtain more insight into the mechanism of this stereochemical control in microbial reduction, β-keto ester reductases were isolated and purified from the cells of G. candidum. Three dominantly competing enzymes were purified. One of them affords the anti-(2S,3S)-hydroxy ester selectively, whereas the others give the syn-(2R,3S)-hydroxy ester selectively. The rates of enzymatic reductions were measured in the presence and absence of an additive. Chloroacetone and MVK are competitive and suicide substrates, respectively, for the syn-enzymes, whereas they hardly affect the activity of the anti-enzyme. In the presence of an additive, the reduction of ethyl 2-methyl-3-oxobutanoate with G. candidum is catalyzed by the anti-enzyme only.
Synthesis and Properties of High-Molecular-Weight Polypeptides Containing Tryptophan III. Synthesis and Properties of Copolypeptides Containing 1-Nin-Formyltryptophan with Alanine
Authors: Uchida Chieko , Wakamatsu Kaori , Iizuka Yasuko , Oguma Kouki , Oya Masanao 
Published: June 2006

Abstract
N-Carboxy-Nin-formyltryptophan anhydride (4-(l-1-Nin-formylindol-3-ylmethyl)-2,5-oxazolidine dione, Trp(Form) NCA) was synthesized by formylation of the indole group of tryptophan, followed by N-carboxylation. The reactivity of copolymerization of Trp(Form) NCA with N-carboxy-l-alanine anhydride (4-methyl-1-2,5-oxazolidinedione, l-Ala NCA) was higher than that of Trp NCA. The helix contents of the formed copolypeptides, estimated by CD spectra, were remarkably decreased at a content of about 27% of Trp(Form). The content of Trp(Form) residue needed to destroy helix conformation in the copolypeptides was more than that of Trp residue of 8%.
Photocatalytic Formations of Patterning Dye Films with TiO2 Particles Based on Chromogenic Development of Photography
Authors: Liu Shunlin , Saji Tetsuo 
Published: June 2006

Abstract
Patterning dye films were obtained on a transparent polyester plate by ultraviolet (UV) light illumination of an alkaline suspension containing TiO2 particles, methylviologen dichloride (MVCl2), N,N-p-phenylenediamine (PPD), and coupler. The patterning films formed are of high resolution (10 μm). Influences of light intensity (Φ), amount of TiO2 particles, solution acidity, and illumination time on the film formation were studied. Regeneration of MV2+ by oxygen was found to be important for film formation.
pH-Modulated Vectorial Electron Transfer Reactions at a Self-Assembled Monolayer on a Gold Electrode
Authors: Nakashima Naotoshi , Deguchi Yonekazu 
Published: June 2006

Abstract
A self-assembled monolayer of 1-dodecanethiol (C12SH) on a gold electrode was prepared by dipping a polished bare electrode into an ethanolic solution of C12SH (1.0 mmol dm−3) for 10 min. The obtained modified electrode blocked the direct electron-transfer reaction of [Fe(CN)6]3− and [Fe(CN)6]4− with the underlying electrode. However, a pH-dependent redox compound, 4,4′-biphenyldiol (1) in solution, was permeable into the monolayer and gave well-defined cyclic voltammograms at both higher and lower pHs. Using this chemical-recognition ability of the modified electrode together with the formal potential shift of 1 according to the Nernst equation, pH–modulated vectorial electron transfer reactions were examined. At pH 3, cyclic voltammograms at the modified electrode in a 1 + [Fe(CN)6]4− aqueous solution revealed that one-way electron flow from [Fe(CN)]4− to the electrode via1 (oxidized form) occurred. On the contrary, at higher pHs (pH 9—11), the vectorial electron flow at the electrode in 1 + [Fe(CN)6]3− solution was reversed. A triggered change (‘switching’) between the anodic and cathodic vectorial electron transfer reactions by changing the pH was also possible at the C12SH-modified electrode in the presence of 1, [Fe(CN)6]4− and [Fe(CN)6]3− in solution. This finding may offer possibilities for the construction of functional molecular devices based on the tuning of rectified electron transfer reactions.
Order–Disorder Transition in a Dioctadecyldimethylammonium Chloride LB Film Studied by FT-IR ATR Spectroscopy
Authors: Kawai Takeshi 
Published: June 2006

Abstract
An order–disorder process in Langmuir–Blodgett (LB) films of dioctadecyldimethylammonium chloride (DODAC) has been studied by FT-IR ATR spectroscopy. This order–disorder process gradually occurred over a wide temperature range, and the transition was shifted to a higher temperature with the number of monolayers. In DODAC LB films immersed in water a similar thermotropic phase behavior was observed, except for the transition temperature. However, this behavior completely differed from that of cast film.