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Gu W.,Yunnan University | Yang J.,Yunnan University | Lou Z.,Tsinghua University | Liang L.,Yunnan University | And 8 more authors.

Microbial ferulic acid decarboxylase (FADase) catalyzes the transformation of ferulic acid to 4-hydroxy-3-methoxystyrene (4- vinylguaiacol) via non-oxidative decarboxylation. Here we report the crystal structures of the Enterobacter sp. Px6-4 FADase and the enzyme in complex with substrate analogues. Our analyses revealed that FADase possessed a half-opened bottom β-barrel with the catalytic pocket located between the middle of the core β-barrel and the helical bottom. Its structure shared a high degree of similarity with members of the phenolic acid decarboxylase (PAD) superfamily. Structural analysis revealed that FADase catalyzed reactions by an "open-closed" mechanism involving a pocket of 8×8×15 Å dimension on the surface of the enzyme. The active pocket could directly contact the solvent and allow the substrate to enter when induced by substrate analogues. Site-directed mutagenesis showed that the E134A mutation decreased the enzyme activity by more than 60%, and Y21A and Y27A mutations abolished the enzyme activity completely. The combined structural and mutagenesis results suggest that during decarboxylation of ferulic acid by FADase, Trp25 and Tyr27 are required for the entering and proper orientation of the substrate while Glu134 and Asn23 participate in proton transfer. © 2011 Gu et al. Source

Geng Z.-L.,CAS Kunming Institute of Botany | Geng Z.-L.,Guizhou Tobacco Research Institute | Fang X.,CAS Kunming Institute of Botany | Di Y.-T.,CAS Kunming Institute of Botany | And 3 more authors.
Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences

A new limonoid, trichiliton B (1), was isolated from the twigs and leaves of Trichilia connaroides. Its structure was elucidated on the basis of spectroscopic analyses, including application of ESI-MS, HR-ESI-MS, UV, IR, 1D and 2D NMR techniques. © 2010 Verlag der Zeitschrift für Naturforschung, Tübingen. Source

Ma Y.,Tongren Tobacco Company | Luo H.,Tongren Tobacco Company | Song J.,Tongren Tobacco Company | Mo J.,Tongren Tobacco Company | And 4 more authors.
Acta Tabacaria Sinica

Relationships between humus chemical composition and soil factors in typical tobacco-growing regions were analyzed. Results showed that: (1) carbon content (TC) of soil humus ranged from10 g/kg to 20 g/kg, with average of 15.25 g/kg. Proportions of humic acid (HA), fulvic acid (FA) and humin (HM) in humus carbon content were distributed in 11.05%-32.15%, 12.00%-36.28% and 38.43%-68.23%, respectively. Most of HA/FA ratios ranged from 0.7 to 1.3; (2) TC in tobacco growing regions in southeast China was significantly higher than in other regions, with Huanghuai region was the lowest. The HA/FA ratio of tobacco growing regions in southeast China was significantly higher than in others, with an average value of 1.14, while in other regions it was less than 1; (3) Carbon levels of TC and humus composition in paddy soil were the highest followed by purple, red, and brown soils. The humification degree of paddy soil was also much higher than others; (4) soil pH values were significantly negatively correlated with humus composition. Alkali-hydrolyzable nitrogen content increased with decreasing soil FA/TC, or increasing HA/FA. Source

Li Z.,Guizhou Tobacco Research Institute | Liu Y.,Guizhou Tobacco Research Institute | Chen H.,Yangtze University | Chen Y.,Guizhou Tobacco Research Institute | Long M.,Guizhou Tobacco Research Institute
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering

An agar bed was developed which corresponds to a traditional paper bed, and which can be used for testing tobacco seed germination. Unprocessed seeds, primed seeds, and pelleted seeds of K326, Yun-87, and Nanjiang-3 were germinated on agar beds of different concentrations, with filter paper used as a control. When the agar concentration was 0.55%, seeds grew significantly faster than the control during early germination (p<0.05); when it was greater than 1.65%, seedlings of naked seeds wilted on the 9 th day and pelleted seeds wilted on the 10 th day; when the agar concentrations were 0.8% and 1.1%, there were no significant differences in germinative energy or germinative percentage compared with the control (p<0.05). agar can maintain a certain amount of water used for seed germination, and needn't shower water in the whole cycle. Seeds were easy to sow and count because they cling lightly to the agar medium and did not roll as in the control. Source

Lei B.,Guizhou Tobacco Research Institute | Zhao X.-H.,Southwest University | Zhang K.,Southwest University | Zhang J.,Guizhou Tobacco Research Institute | And 11 more authors.
Molecular Biology Reports

To identify genes that are differentially expressed in tobacco in response to environmental changes and to decipher the mechanisms by which aromatic carotenoids are formed in tobacco, an Agilent Tobacco Gene Expression microarray was adapted for transcriptome comparison of tobacco leaves derived from three cultivated regions of China, Kaiyang (KY), Weining (WN) and Tianzhu (TZ). A total of 1,005 genes were differentially expressed between leaves derived from KY and TZ, 733 between KY and WN, and 517 between TZ and WN. Genes that were upregulated in leaves from WN and TZ tended to be involved in secondary metabolism pathways, and included several carotenoid pathway genes, e.g., NtPYS, NtPDS, and NtLCYE, whereas those that were down-regulated tended to be involved in the response to temperature and light. The expression of 10 differentially expressed genes (DEGs) was evaluated by real-time quantitative polymerase chain reaction (qRT-PCR) and found to be consistent with the microarray data. Gene Ontology and MapMan analyses indicate that the genes that were differentially expressed among the three cultivated regions were associated with the light reaction of photosystem II, response to stimuli, and secondary metabolism. High-performance liquid chromatography (HPLC) analysis showed that leaves derived from KY had the lowest levels of lutein, β-carotene, and neoxanthin, whereas the total carotenoid content in leaves from TZ was greatest, a finding that could well be explained by the expression patterns of DEGs in the carotenoid pathway. These results may help elucidate the molecular mechanisms underlying environmental adaptation and accumulation of aroma compounds in tobacco. © 2012 Springer Science+Business Media Dordrecht. Source

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