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Volume 39, Issue 7
Displaying 51-58 of 58 articles from this issue
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Hiromasa TAKIZAWA, Tetsuo NAGANO, Masaaki HIROBE1991 Volume 39 Issue 7 Pages 1894-1896
Published: July 25, 1991
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSEnones can be epoxidized by O2-· in the presence of various compounds having an acidic >NH group. Cyclic voltammetry and ESR study show that O2-· was disproportionated into H2O2 and O2 by these compounds. Furthermore, H2O2 was deprotonated by unreacted O2-· and HOO- was formed, which is widely known to be the effective oxidant in the epoxidation of enones. This confirms the strong basicity of O2-· in aprotic media, and we propose an alternative scheme for the Haber-Weiss reaction in the absence of metal ions.View full abstractDownload PDF (481K) -
Kazutake SHIMADA, Tomoyuki OE1991 Volume 39 Issue 7 Pages 1897-1898
Published: July 25, 1991
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSA novel derivatization reagent with tetrathiafulvalene as an electrophore, N-succinimidyl tetrathiafulvalene-2-carboxylate, was prepared and evaluated for pre-column labeling of amine by using β-phenethylamine as a model compound in high-performance liquid chromatography with electrochemical detection. The reagent reacted readily with the primary amine at room temperature for 1 h, providing the amide which was highly responsive to an electrochemical detector (detection limit = 21 fmol, signal to noise ratio = 5) at a relatively low applied potential (+700 mV vs. Ag/AgCl). The characteristic two-stage oxidative pattern appeared on the hydrodynamic voltammogram of the derivative, which helped to identify the peak on the chromatogram.View full abstractDownload PDF (370K) -
Norio MASAKI, Katsunosuke MACHIDA, Hiroyuki KADO, Kazuo YOKOYAMA, Taka ...1991 Volume 39 Issue 7 Pages 1899-1901
Published: July 25, 1991
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSThe atomic force microscope has been developed and used to iamge arrays of molecures at the (001) and (100) faces of aspirin crystals in water and in air. Lattice spacings composed of methyl groups and the part of the phenyl groups on the surface of the (001) in water, are consistent with X-ray diffraction data. The surface of (100) face which shows most perfect cleavage in bulk, is more difficult to image. This initial success in imaging at drug crystal surfaces clarified the different structural behavior at the submolecular level for three crystal faces, and the close relation-ship to the differences in the dissolution velocity.View full abstractDownload PDF (699K) -
Yukio KITADE, Ryuji NAKANISHI, Magoichi SAKO, Kosaku HIROTA, Yoshifumi ...1991 Volume 39 Issue 7 Pages 1902-1904
Published: July 25, 1991
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSFacile conversion of N6-benzoyl-2', 3'-O-isopropylideneadenosine (1) into N6-benzoyl-5'-chloro-5'-deoxy-8-hydroxy-2', 3'-O-isopropylideneadenosine (3) by a reaction with cupric chloride in acetonitrile provides a new method for the chemical modification of adenosines. This reflects the prominent substitutent effect of N6-benzoyl group on the chemical reactivity of adenosines.View full abstractDownload PDF (396K) -
Masanori SOMEI, Toshiya KAWASAKI, Kazuhisa SHIMIZU, Yoshikazu FUKUI, T ...1991 Volume 39 Issue 7 Pages 1905-1907
Published: July 25, 1991
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSMethyl 1-hydroxyindole-3-acetate, (±)-2-acetoamino-3-(10hydroxyindol-3-yl)propanol, N__-b-acetyl-1-hydroxytryptamine, (±)- and (S__-)-(+)-N__-b-acetyl-1-hydroxytryptophan methyl ester, which are needed for inspecting our hypothesis regarding the metabolism of tryptophan, were prepared for the first time. The structural proof of (±)-N__-b-acetyl-1-hydroxytryptophan methyl ester by X-ray crysatllographic analysis is also reported.View full abstractDownload PDF (480K) -
Takashi TAKESHITA, Kei YOKOYAMA, Ding YI, Junei KINJO, Toshihiro NOHAR ...1991 Volume 39 Issue 7 Pages 1908-1910
Published: July 25, 1991
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSFour new oleanene sapogenols having 22-oxo group were obtained from the methanolysate of the crude glycosidic fraction in Sophorae Subprostratae Radix, the root of Sophora subprostrate CHUN et T. CHEN. Also, twelve known sapogenols were isolated from the same methanylsate.View full abstractDownload PDF (423K) -
Osamu NAKAJIMA, Takumi AKIYAMA, Takashi HAKAMATSUKA, Masaaki SHIBUYA, ...1991 Volume 39 Issue 7 Pages 1911-1913
Published: July 25, 1991
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESScDNA clones for chalcone synthase (CHS) of Pueraria lobata cultured cells were isolated by screening the cDNA library using CHS cDNA of Phaseolus vulgaris as a probe. Analysis of nucleotide sequences of the cloned cDNA revealed a 1170-bp open reading frame that encoded a 390-amino acid polypeptide with an Mr of 43, 000. The full-length cDNA was cloned into the expression vector pT7-7. CHS activity was found in the crude extracts of transformed E. coli after induction and two protein bands of ca. 43 and 34 kd were hybridized with anti-persley CHS antiserum.View full abstractDownload PDF (667K) -
Tetsuo NAGANO, Maki TAKAHASHI, Masaaki HIROBE1991 Volume 39 Issue 7 Pages 1914-1916
Published: July 25, 1991
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESS1, 6, 6a-Trithia-3, 4-diazapentalenes, which are hypervalent compounds, were reduced electrochemically and the resulting anion radicals reacted with dioxygen (O2) to be re-oxidized to the starting materials, with the production of superoxide (O2-·). We have already reported that 1, 6-dioxa-6a-thia-2, 5-diazapentalenes mediate O2-· production in living cells and do serious damage to the cells. These results suggest that hypervalent heteropentalenes generally generate O2-· in the presence of O2 by chemical or biological reduction system.View full abstractDownload PDF (410K)