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Shigeru SHIGEOKA
Article type: Article
2005 Volume 79 Issue 3 Pages
133-141
Published: March 25, 2005
Released on J-STAGE: October 10, 2017
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Ascorbate (AsA) is contained at high levels in photosynthetic organisms and serves as a scavenger of active oxygen species (AOS). Furthermore, it acts as an enzyme activator by maintaining prosthetic metal ions in the reduced form. Photosynthetic organisms are prone to oxidative stress because of the highly energetic reactions of photosynthesis and an abundant 0_2 supply. The imposition of biotic and abiotic stress conditions can give rise to excess concentrations of AOS, resulting in oxidative damage at the cellular level. Therefore, photosynthetic organisms have developed antioxidant defense systems. Ascorbate peroxidase (APX) isoenzymes are key enzymes for AOS-scavenging systems and are widely distributed in chloroplasts, microbodies, mitochondria, and cytosol of photosynthetic organisms. One of the most characteristic properties of APX isoenzymes is the instability in the absence of AsA. To determine the structure-function relation and to obtain the stereochemical information about the mechanisms of the rapid inactivation of APX isoenzymes, we carried out an X-ray crystallographic analysis for the recombinant stromal soluble APX (sAPX) of tobacco plants.
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Takashi TAMURA
Article type: Article
2005 Volume 79 Issue 3 Pages
143-153
Published: March 25, 2005
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Selenium is an essential trace element for mammals, birds, and some bacteria. Its remarkable biological effects in eukaryotes may be related to unique functions of various selenoproteins. A^<75>Se-labeled protein was purified from a human lung adenocarcinoma cell line, NCI-H441 . A homodimer of 57-kDa subunits contained selenium in the form of selenocysteine. The selenoprotein contained FAD as a prosthetic group and catalyzes NADPH-dependent reduction of insulin in the presence of thioredoxin. The subunit composition and catalytic properties were identical to those of mammalian thioredoxin reductase (TrxR). This was the first report on the biochemical relevance between selenium and Trx-mediated metabolic regulation. Interestingly, human lung adenocarcinoma cells produced the selenoenzyme TrxR over hundred times that of normal mammalian cells. A Iabile selenium donor compound monoselenophosphate, required for selenoprotein biosynthesis, is synthesized from selenide and ATP by selenophosphate synthetase (SPS).
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Yoshitane KOJIMA, Yutaka YOSHIKAWA
Article type: Article
2005 Volume 79 Issue 3 Pages
155-165
Published: March 25, 2005
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The insulinomimetic activities of Zn(II) complexes with various kinds of organic compounds in rat adipocytes treated with epinephrine in terms of inhibition of free fatty acid release have been studied. For the in vitro mechanism, such Zn(II) complexes have been revealed to act exclusively on the glucose transporter (GLUT 4) of the cells. Also, the improvement of glucose tolerance for KK-A^y mice with type 2 diabetes mellitus was obtained by i.p. administrations of Zn(II) complexes, following the finding of in vitro insulinomimetic activity. Furthermore, we found that the complex formation between Zn^<2+> ion and organic compounds reduced the toxicity of Zn^<2+> ion.
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[in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
167-168
Published: March 25, 2005
Released on J-STAGE: October 10, 2017
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[in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
169-170
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
170-171
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
172-173
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
175-
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
175-
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
175-176
Published: March 25, 2005
Released on J-STAGE: October 10, 2017
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
177-
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
177-178
Published: March 25, 2005
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A. C. Ross, R. Zolfaghari, [in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
178-
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
178-179
Published: March 25, 2005
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[in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
181-
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
181-182
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
182-183
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
183-184
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
2005 Volume 79 Issue 3 Pages
184-185
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
185-186
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
186-187
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
187-188
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
2005 Volume 79 Issue 3 Pages
188-
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
2005 Volume 79 Issue 3 Pages
188-189
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
190-
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
190-191
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
191-192
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
192-193
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
193-194
Published: March 25, 2005
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[in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
194-
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
194-195
Published: March 25, 2005
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[in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
197-198
Published: March 25, 2005
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[in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
198-199
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
199-200
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
200-202
Published: March 25, 2005
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
202-203
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
203-205
Published: March 25, 2005
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[in Japanese]
Article type: Article
2005 Volume 79 Issue 3 Pages
205-
Published: March 25, 2005
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