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Volume 82, Issue 2
Displaying 1-8 of 8 articles from this issue
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Toshiharu YagiArticle type: Article
2008 Volume 82 Issue 2 Pages 87-99
Published: February 25, 2008
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSVitamin B_6, consisting of natural six forms, pyridoxine, pyridoxal, pyridoxamine and their 5'-phosphate forms, functions as the essential nutrient through supporting the enzymes involved in metabolisms of amino acids and others as a coenzyme. They nutritionally show the same efficiency, because they can be interchangeable through a salvage pathway to form the coenzyme form, pyridoxal 5'-phosphate. In contrast, recent works show that the individual form has a specific function, such as anti-active carbonyl and antioxidation ones. We have found that vitamin B_6 compounds protected fission yeast cells against oxidative death more efficiently than vitamin C, and inhibited tyrosinase reaction by scavenging reactive oxygen specie(s) essential for the enzyme reaction. The genes encoding enzymes involved in the metabolism of vitamin B_6 compounds were identified, and structures and functions of the enzymes were elucidated. Pyridoxal reductase in the fission yeast cells was a new member of aldo-keto reductase superfamily, and suggested to be involved in an efflux system of pyridoxal after reducing to pyridoxine. All of genes involved in the degradation for vitamin B_6 were identified. They located on a chromosome of Mesorhizobium loti, a nitrogen-fixing symbiotic microorganism, as a cluster. The enzymes were over-expressed and characterized. E. coli cells containing the high amount of the enzymes were used for bioconversion of pyridoxine to 4-pyridoxolactone. Three of the enzymes were applied to a new individual determination method of vitamin B_6 compounds.View full abstractDownload PDF (1975K) -
Hiroko IkushiroArticle type: Article
2008 Volume 82 Issue 2 Pages 101-114
Published: February 25, 2008
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSSerine palmitoyltransferase (SPT) is a key enzyme of sphingolipid biosynthesis and catalyzes the decarboxylative condensation of L-serine with palmitoyl-CoA to form 3-ketodihydrosphingosine. Eukaryote SPTs are known as heterodimers composed of tightly membrane-bound subunits, which makes their detailed analysis difficult. Therefore, as the alternative enzyme source, we focused into the bacteria that contain a large amount of sphingolipid as their cellular component. We have purified a water-soluble homodimeric SPT from Sphingomonas paucimobilis 2395^T first, then cloned SPT genes from several bacterial species and have overproduced them in E. coli. Using these bacterial enzymes, the reaction mechanism of SPT was analyzed in detail and X-ray crystallographic analysis of its structure in a complex with the amino acid substrate, L-serine were performed. These results allow us to understand the structure-function relationship of eukaryote SPT.View full abstractDownload PDF (1931K) -
Katsumi Shibata, Tsutomu FukuwatariArticle type: Article
2008 Volume 82 Issue 2 Pages 115-125
Published: February 25, 2008
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSIn Japan, two basic texts are used for nutritional guidance, Standard Tables of Food Composition in Japan and Dietary Reference Intakes for Japanese, 2005. The "Food Composition Tables" describe the nutrient values of foods, and "Dietary Reference Intakes" reports the values that humans can use. Synthetic vitamins have been often used in experiments to determine vitamin requirements, and the bioavailability of synthetic vitamins is considered to be 100%. However, the bioavailability of a vitamin from foods may not be 100% because most vitamins existing in nature are bound to proteins, sugars, or other compounds. Although it is necessary to determine the bioavailability of vitamins in food consumed, no method has been established. We introduce a practical method to determine the bioavailability of vitamins in food. In particular, we are also interested in the effects the dietary intake of minerals and micronutrients exerts on the bioavailability of vitamins. We believe that the results of these studies will contribute to the maintenance of public health in Japanese.View full abstractDownload PDF (1037K) -
Mari Kigawa, Shinsuke KataokaArticle type: Article
2008 Volume 82 Issue 2 Pages 127-130
Published: February 25, 2008
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSIn vivo evaluating model is accepted as a powerful tool for determining pharmaceutical effects and safe dosage for clinical use. We established the animal model for evaluating the inflammation caused by reactive oxygen species (ROS). Croton oil (CRO) was topically applied to induce ROS-derived inflammation on the guinea pig skin. Visual inspection of the erythema was performed on 24h after application to evaluate the CRO-induced skin response on a score of one to six. Ascorbate-2-phosphate (AP), ascorbic acid derivative, has been reported to be a potent antioxidant action. To examine its effect on this model, AP was applied topically after CRO application. The inflammation score was significantly reduced by 32-52% of that in the control group. Histological evaluation revealed that AP also decreased the inflammatory thickening and the expression of the oxidative stress marker, 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the skin. These results show the CRO-induced inflammation model developed here is useful tool for evaluating anti-inflammatory and antioxidant effects.View full abstractDownload PDF (1087K) -
Katsumi Shibata, Junko Hirose, Tsutomu Fukuwatari, Yoshifumi Hida, Tak ...Article type: Article
2008 Volume 82 Issue 2 Pages 131-135
Published: February 25, 2008
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSThe blood NAD(H) level varies with animal species, whereas the blood NADP(H) concentration is the same in all animal species. Because little is known about the blood NAD(H) and NADP(H) concentrations in water animals, we investigated the concentrations of both in nigorobuna, Carassius auratus grandoculis. Fifty nigorobuna (0+years old) were harvested from Lake Biwa, Seventeen of them were aquacultured and then released into the lake, 9 of them were transferred to a paddy field for one or two months after hatching and then released into the lake, and 24 of them were born and grew up in the natural environment. The blood NAD(H) concentration in nigorobuna was approximately 80nmol/mL, which is almost the same as that of rats and 2.5 times higher than that of humans. The blood NADP(H) concentration in nigorobuna was approximately 2.5nmol/mL, which is one fourth of the values in rats and humans. There were no differences in blood NAD(H) and NADP(H) levels by sex or life history in nigorobuna.View full abstractDownload PDF (604K) -
Keiko Tazuya(Murayama), Kazuko Yamada, Motohiro MishimaArticle type: Article
2008 Volume 82 Issue 2 Pages 137-139
Published: February 25, 2008
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSDownload PDF (363K) -
Mamoru Igarashi, Shigeaki KatoArticle type: Article
2008 Volume 82 Issue 2 Pages 140-141
Published: February 25, 2008
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSDownload PDF (266K) -
Hiroki KondoArticle type: Article
2008 Volume 82 Issue 2 Pages 142-
Published: February 25, 2008
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSDownload PDF (137K)
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