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Loosening Xyloglucan Accelerates the Enzymatic Degradation of Cellulose in Wood

Molecular Plant 2009年第5期2卷 904-909页

作者： Rumi Kaida Tomomi Kaku Kei'ichi Baba Masafumi Oyadomari Takashi Watanabe Koji Nishida Toshiji Kanaya Ziv Shani Oded Shoseyov Takahisa Hayashi Kyoto University RISH Gokasho Uji Kyoto 611-0011 Japan Kyoto University Institute for Chemical Research Gokasho Uji Kyoto 611-0011 Japan CBD Technologies Rehovot 76100 Israel Institute of Sustainability Science Kyoto University Gokasho Uji Kyoto 611-0011 Japan

In order to create trees in which cellulose, the most abundant component in biomass, can be enzymatically hydrolyzed highly for the production of bioethanol, we examined the saccharification of xylem from several transgenic poplars, each overexpressing either xyloglucanase, cellulase, xylanase, or galactanase. The level of cellulose degradation achieved by a cellulase preparation was markedly greater in the xylem overexpressing xyloglucanase and much greater in the xylems overexpressing xylanase and cellulase than in the xylem of the wild-type plant. Although a high degree of degradation occurred in all xylems at all loci, the crystalline region of the cellulose microfibrUs was highly degraded in the xylem overexpressing xyloglucanase. Since the complex between microfibrils and xyloglucans could be one region that is particularly resistant to cellulose degradation, loosening xyloglucan could facilitate the enzymatic hydrolysis of cellulose in wood.

关键词： Overexpression of xyloglucanase saccharification transgenic poplar xylem.

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Synthesis and Enhanced Guest-Binding Affinities of Dendrimer-Based Cyclophane Tetramer and Octamer

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Advances in Chemical Engineering and Science 2013年第3期3卷 33-37页

作者： Osamu Hayashida tomomi Nakashima Yu kaku Department of Chemistry Faculty of Science Fukuoka University Fukuoka Japan

Dendritic cyclophane tetramer and octamer were prepared by aminolysis of succinimidyl ester derivative of tetraaza [6.***.6.1] paracyclophane with the corresponding poly(amidoamine) dendrimers as a scaffold, followed by removal of the protecting groups. The present cyclophane tetramer and octamer showed enhanced guest-binding affinities toward fluorescent guests such as 6-p-toluidinonaphthalene-2-sulfonate and 6-anilinonaphthalene-2-sulfonate, in comparison with those of monocyclic cyclophane, reflecting multivalency effects in macrocycles.

关键词： Cyclophane Oligomer Host-Guest Chemistry Multivalency Effect

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Xyloglucan for Generating Tensile Stress to Bend Tree Stem

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Molecular Plant 2009年第5期2卷 893-903页

作者： Kei'ichi Baba Yong Woo Park Tomomi Kaku Rumi Kaida Miyuki Takeuchi Masato Yoshida Yoshihiro Hosoo Yasuhisa Ojio Takashi Okuyama Toru Taniguchi Yasunori Ohmiya Teiji Kondo Ziv Shani Oded Shoseyov Tatsuya Awano Satoshi Serada Naoko Norioka Shigemi Norioka Takahisa Hayashi Kyoto University RISH Gokasho Uji Kyoto 611-0011 Japan Graduate School of Bioagricultural-Sciences Nagoya University Nagoya 464-8601 Japan Forest Tree Breeding Center Hitachi Ibaraki 319-1301 Japan CBD Technologies Rehovot 76100 Israel Division of Forest and Biomaterials Science Kyoto University Kyoto 606-8502 Japan Graduate School of Frontier Biosciences Osaka University Suita Osaka 565-0871 Japan Institute of Sustainability Science Kyoto University Gokasho Uji Kyoto 611-0011 Japan

In response to environmental variation, angiosperm trees bend their stems by forming tension wood, which consists of a cellulose-rich G （gelatinous）-Iayer in the walls of fiber cells and generates abnormal tensile stress in the secondary xylem. We produced transgenic poplar plants overexpressing several endoglycanases to reduce each specific polysaccharide in the cell wall, as the secondary xylem consists of primary and secondary wall layers. When placed horizontally, the basal regions of stems of transgenic poplars overexpressing xyloglucanase alone could not bend upward due to low strain in the tension side of the xylem. In the wild-type plants, xyloglucan was found in the inner surface of G-layers during multiple layering. In situ xyloglucan endotransglucosylase （XET） activity showed that the incorporation of whole xyloglucan, potentially for wall tightening, began at the inner surface layers S1 and S2 and was retained throughout G-layer development, while the incorporation of xyloglucan heptasaccharide （XXXG） for wall loosening occurred in the primary wall of the expanding zone. We propose that the xyloglucan network is reinforced by XET to form a further connection between wall-bound and secreted xyloglucans in order to withstand the tensile stress created within the cellulose G-layer micro fibrils.

关键词： G-layer tensile stress xyloglucan xyloglucan endotransglucosylase

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