VITAMINS
Online ISSN : 2424-080X
Print ISSN : 0006-386X
Volume 80, Issue 12
Displaying 1-12 of 12 articles from this issue
  • Misa Ogushi, Shuhei Ebara, Toru Fukui, Toshiaki Watanabe
    Article type: Article
    2006 Volume 80 Issue 12 Pages 579-585
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
    There are little scientific data to estimate the dietary reference intake of vitamins in Japan. New additional information is needed on the requirements and dietary intake for folate. Therefore, this study was designated to evaluate the dietary folate intake and the serum folate concentration in middle-aged and elderly population (n=120, 61.7±8.5y) in Japan. The dietary folate intake was 442±119μg/day and 432±118μg/day for the annual average in men and women, respectively. There were no large differences between sexes. On the other hand, the folate concentration in the serum was 5.8±2.2ng/ml for the annual average in men, which significantly differed from 7.8±2.8ng/ml in women (p<0.05). The serum folate concentration was highest in summer and lowest in winter. A seasonal variation in both men and women was clearly observed. From these findings, it is suggested that the recommended dietary allowance for folate should be estimated, primarily taking into account a sex difference.
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  • Hisaaki Mihara, Nobuyoshi Esaki
    Article type: Article
    2006 Volume 80 Issue 12 Pages 587-595
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
    Pyridoxal 5'-phosphate-dependent enzymes, selenocysteine lyase (SCL) and cysteine desulfurase, occur in a variety of organisms. SCL catalyzes the decomposition of L-selenocysteine to form L-alanine and an enzyme-bound cysteine perselenide (Cys-Se) intermediate. Cysteine desulfurase catalyzes the same type of reaction as SCL but acts on L-cysteine as a substrate to form an cysteine persulfide (Cys-SH) on the active site residue. We carried out comparative studies between SCL and cysteine desulfurase to investigate functional and mechanistic characteristics of the family of the enzymes. Spectrum analyses showed that L-cysteine enters into the active site pocket of SCL but can not form an external aldimine complex with PLP. The formation of an external aldimine complex between SCL and L-selenocysteine requires the active-site nucleophile Cys375. Thus, Cys375 of SCL plays a central role in the discrimination between selenium and sulfur in a substrate and its analog.
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  • Tetsuo Toraya
    Article type: Article
    2006 Volume 80 Issue 12 Pages 597-606
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
    Vitamin B_<12> compounds have been intriguing subjects of investigation for inorganic and organometallic chemists for a long time, because vitamin B_<12> and its coenzyme forms are a cobalt complex and organocobalt compounds, respectively. Recently, many X-ray structures of B_<12>-dependent enzymes have become available, and the functional roles of B_<12> coenzymes in enzymatic reactions have been elucidated on the bases of their three-dimensional structures. The fine mechanisms of B_<12> catalyses in these enzymes are the main subjects of this review. In addition, some B_<12> enzymes contain metal ions other than B_<12> coenzymes and their roles are interesting. Furthermore, in some non-B_<12> but isofunctional enzymes, metal ion-containing components seem to function as a substitute for B_<12>. The biochemistry of these types of metal ions that are related to the functions of B_<12> is also included in this review.
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  • [in Japanese]
    Article type: Article
    2006 Volume 80 Issue 12 Pages 607-609
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
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  • [in Japanese], [in Japanese]
    Article type: Article
    2006 Volume 80 Issue 12 Pages 610-612
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
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  • [in Japanese]
    Article type: Article
    2006 Volume 80 Issue 12 Pages 613-616
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
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  • Article type: Bibliography
    2006 Volume 80 Issue 12 Pages 617-622
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
    Article type: Article
    2006 Volume 80 Issue 12 Pages 623-624
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
    Article type: Article
    2006 Volume 80 Issue 12 Pages 624-625
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese]
    Article type: Article
    2006 Volume 80 Issue 12 Pages 625-
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese]
    Article type: Article
    2006 Volume 80 Issue 12 Pages 625-626
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
    Download PDF (353K)
  • [in Japanese]
    Article type: Article
    2006 Volume 80 Issue 12 Pages 626-
    Published: December 25, 2006
    Released on J-STAGE: October 10, 2017
    JOURNAL FREE ACCESS
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