Structural probing of D-fructose derived ligands for asymmetric addition of diethylzinc to aldehydes

A series of new chiral ligands derived from D-fructose have been synthesized and applied in the enantioselective addition of diethylzinc to aldehydes. Comparison of the enantioselectivities obtained with these ligands demonstrated that the catalytic properties are highly dependent upon the structure of ligands, a rational explanation of the structural effects on the catalytic properties is provided. (C) 2003 Elsevier Science Ltd. All rights reserved.

不同葡萄糖/果糖类型桃果实发育期间可溶性糖的变化规律和代谢

以成熟果实中不同葡萄糖/果糖（G/F）类型的6个桃品种（G/F≈1品种：‘冈山白’、‘山一白桃’和‘燕红’;高G/F品种：‘张黄7号’、‘龙246’和‘临白7号’）为试材，采用高效液相色谱法测定果实发育期果实和叶片中可溶性糖含量，并在盛花后74 d或101 d测定了‘冈山白’、‘山一白桃’、‘张黄 7号’和‘龙 246’新梢韧皮部中可溶性糖的含量;测定了果实发育过程中‘山一白桃’和‘临白7号’果实中的可溶性糖和淀粉代谢相关酶的活性。研究成熟果实中不同G/F类型桃果实内G/F差异的部位和时期;分析桃果实内G/F差异的可溶性糖代谢调控机理。 成熟果实中不同G/F类型桃果实中均以蔗糖作为主要碳水化合物积累形式，花后43–85 d蔗糖含量很低，随后持续快速积累直至果实成熟;花后43–85 d山梨醇有升高趋势，在果实成熟前40 d左右迅速降低;葡萄糖和果糖含量在果实发育早期较高，之后逐渐降低;但两类不同G/F桃在整个果实发育过程中G/F值与果实成熟时相似。叶片中贮藏的可溶性糖主要是蔗糖和山梨醇，在果实整个发育期间，G/F≈1品种叶片中G/F约1-3，而高G/F品种叶片中G/F约为2-7。G/F≈1品种‘冈山白’和‘山一白桃’与高G/F品种‘张黄 7号’和‘龙 246’韧皮部中山梨醇占总可溶性糖47-63％，显著高于蔗糖、葡萄糖和果糖的含量，G/F为0.8-0.91，且两类不同G/F桃品种间G/F值不存在显著差异。 成熟果实中G/F≈1类型的‘山一白桃’和高G/F值类型的‘临白7号’整个果实发育过程中，葡萄糖、山梨醇和淀粉的含量在这两个品种间一般没有明显差异;‘山一白桃’果实中的果糖含量显著高于‘临白7号’果实中的果糖;果实最后迅速生长期，‘山一白桃’果实中的蔗糖明显高于‘临白7号’。‘山一白桃’和‘临白7号’果实中的NAD+依赖型山梨醇脱氢酶（NAD+-SDH）活性低，两者有相似的变化趋势，一般无显著差异。‘临白7号’果实中的NADP+依赖型山梨醇脱氢酶（NADP+-SDH）和山梨醇氧化酶（SOX）活性一直高于‘山一白桃’，两者NADP+-SDH和SOX的活性分别在花后93-123 d和花后43-93 d有显著差异。‘临白7号’果实中的果糖激酶（FK）活性一般高于‘山一白桃’。花后43-93 d，‘临白7号’果实中的磷酸蔗糖合成酶（SPS）和蔗糖合成酶（SS）活性一般显著‘山一白桃’。果实最后迅速生长期，蔗糖快速积累，葡萄糖、果糖、山梨醇和淀粉含量迅速降低，同时伴随有SPS和SS活性的迅速升高。在整个果实发育过程中，两个品种果实中的淀粉酶活性较高，其果实中的淀粉含量和淀粉酶活性都有明显的下降趋势。 研究结果表明，整个果实发育过程中桃果实中均存在G/F≈1和高G/F现象，光合产物在韧皮部的运输对桃果实的G/F没有显著的影响，果实中G/F的差异主要由于果实内糖代谢差异所导致。‘临白7号’果实中山梨醇向果糖方向的转化能力与‘山一白桃’一般没有显著差异，由于不同时期较高的NADP+-SDH和SOX活性，使得山梨醇向葡萄糖方向的转化能力明显高于‘山一白桃’，同时，‘临白7号’果实中的FK活性一般高于‘山一白桃’，因此导致‘临白7号’果实中G/F高于‘山一白桃’。

桃不同组织中的葡萄糖/果糖比值特点及己糖代谢

以不同葡萄糖/果糖（G/F）类型的桃品种（正常G/F 品种：‘燕红’、‘冈山白’和‘山一白桃’；高G/F 品种：‘龙124’、‘龙246’、‘张黄7 号’和‘临白7 号’）为试材，测定果实发育期果实、叶片、韧皮部和木质部中糖和淀粉含量，并分别在果实第一迅速生长期、硬核期和成熟期测定了‘燕红’、‘山一白桃’、‘龙124’、‘龙 246’和‘临白7号’果实和叶片中己糖相关酶。研究不同G/F类型桃品种产生G/F差异的组织器官和时期，并且分析相关代谢酶调控机理。 两类不同G/F 桃果实中均以蔗糖作为主要碳水化合物积累形式，花后70 d前蔗糖含量很低，随后快速积累直至果实成熟；山梨醇含量较为稳定，高G/F品种‘龙124’两年间在未成熟果实中山梨醇含量高于正常 G/F品种；葡萄糖和果糖含量在果实第一迅速生长期积累，之后逐渐降低。高 G/F 品种‘龙124’和‘临白7号’成熟果实中葡萄糖含量高于‘龙246’和正常 G/F 品种。正常G/F品种果实、叶片、韧皮部和木质部中葡萄糖和果糖含量基本相等，G/F基本保持在0.7-1.5。高G/F品种果实、叶片中葡萄糖显著高于果糖，果实中G/F在1.6-8.8，叶片中G/F在果实未成熟时为2.5-9.3，在果实成熟期为14.5-21.3。然而韧皮部和木质部中葡萄糖略高于果糖或基本相等，但较正常G/F品种高。因此，光合产物在韧皮部的运输对桃果实的G/F 没有显著影响。 在第一迅速生长期和成熟期时，所有供试桃品种果实和叶片中合成己糖的NAD+-SDH 和 SOX较为活跃，而分解己糖的FRK、GLK和PGI则保持在较低水平；在果核硬化期则相反，果实和叶片中合成己糖的NAD+-SDH 和 SOX活性较低，而分解己糖的FRK、GLK和PGI则较为活跃。高G/F品种‘龙124’和‘龙246’在果核硬化期果实中的FRK、NADP+-SDH 和GLK活性显著高于正常G/F品种，而高G/F品种‘临白7号’则与正常G/F品种没有明显差异。可见，高G/F品种间己糖代谢调控机制也有所差异。此外，叶片中两种G/F类型间的己糖代谢相关酶差异并无明显规律，由此我们认为叶片存在与果实类似但相对独立的调控机制。

Bifunctional enzyme FBPase/SBPase is essential for photoautotrophic growth in cyanobacterium Synechocystis sp PCC 6803

From a random insertion mutant library of Synechocystis sp. PCC 6803, a mutant defective in photoautotrophic growth was obtained. The interrupted gene was identified to be slr2094 (rbpl), which encodes the fructose-1,6-biphosphatase (FBPase)/sedoheptulose-1,7-biphosphatase (SBPase) bifunctional enzyme (F-I). Two other independently constructed slr2094 mutants showed an identical phenotype. The FBPase activity was found to be virtually lacking in an slr2094 mutant, which was sensitive to light under mixotrophic growth conditions. These results indicate that slr2094 is the only active FBPase-encoding gene in this cyanobacterium. Inactivation of photosystem II by interrupting psbB in slr2094 mutant alleviated the sensitiveness to light. This report provides the direct genetic evidence for the essential role of F-I in the photosynthesis of Synechocystis sp. PCC 6803. (c) 2007 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.

酿酒酵母和运动发酵单胞菌木薯乙醇发酵条件研究

本文结合我国燃料乙醇发展的方针政策，以酿酒酵母和运动发酵单胞菌为菌种研究其在非粮能源作物木薯中乙醇发酵的情况，为木薯原料更好地应用于生产中提供了理论依据。 酿酒酵母木薯高浓度乙醇发酵的研究。实验采用的木薯干淀粉含量约70-75%。以酿酒酵母为菌种进行高浓度乙醇发酵的工艺条件研究，最佳条件为：木薯干粉碎细度为35目，料水比1：2，α-淀粉酶用量0.09 KNU/g淀粉，蒸煮温度85 ℃，蒸煮时间15 min。采用30 ℃同步糖化发酵工艺，糖化酶用量为3.4 AGU/g淀粉，发酵时间30 h。在10 L发酵罐中，乙醇质量比达127.88 g/kg，发酵效率为88.28%，发酵强度4.263 g/kg/h，100 L中试研究中乙醇浓度为127.75 g/kg，发酵强度4.258 g/kg/h。利用高效液相色谱对发酵液中残糖进行了分析，证明葡萄糖、果糖等单糖已完全被菌体利用，剩余糖为二糖，三糖等不可发酵的低聚糖。 运动发酵单胞菌快速乙醇发酵的研究。对实验室保藏的8株运动发酵单胞菌进行比较，选择发酵速度最快的Zymomonas mobilis232B进行研究。该菌在纯葡萄糖中的最佳发酵条件为：葡萄糖浓度18%，起始pH 6-7，发酵温度30 ℃，发酵时间18 h，乙醇浓度88 g/kg。在以木薯为底物同步糖化快速乙醇发酵中，采用Full Factorial设计和最速上升实验确定了培养基成分中的2个显著性因子及其最适浓度：酵母粉4 g/kg，硫酸铵0.8 g/kg。在最适培养基条件下，对木薯料水比和糖化酶用量进行了优化，得到Z.mobilis232B木薯乙醇发酵最佳料水比1：3，糖化酶浓度4 AGU/g淀粉，乙醇发酵4.915 g/kg/h。利用高效液相色谱对发酵液中残糖进行了分析，剩余糖为二糖，三糖等，但成分较酵母发酵后复杂。 According to the fuel ethanol development plans and policies in our country, the ethanol production from cassava by Saccharomyces cerevisiae and Zymomonas mobilis was studied. It provided theoretical basis for ethanol fermentation by cassava in industry. Part 1 is the study of VHG (very high gravity) ethanol fermentation by Saccharomyces cerevisiae. The content of starch in cassava was 70-75%. Compared with the performances under different experimental conditions, the following optimal conditions for VHG fermentation were obtained: Granule size of dry cassava 35 mashes, hydromodulus of cassava to water at 1:2, α-amylase enzyme dosage 0.09 KNU/g starch, cooking temperature 85 ℃ for 15 min, using the SSF process (simultaneous saccharification and fermentation) and the amount of glucoamylase 3.4 AGU/g starch. Accordingly, the final ethanol concentration was up to 127.88 g/kg; the ethanol yield reached 88.28%, and ethanol productivity was 4.263 g/kg/h after 30 h. When the fermentation scale expanded to 100 L, the final ethanol concentration was 127.75 g/kg, and the ethanol productivity was 4.258 g/kg/h in 30 h. The residual sugar was analyzed by high performance liquid chromatography, and proved that there was no glucose and fructose. The residual reducing sugar was some unfermentable oligosaccharide Part 2 is the study of the rapid ethanol production by Zymomonas mobilis. Compare with other seven stains, Zymomonas mobilis 232B was selected for research. The optimum condition in glucose medium was as follow: glucose concentration 18%, initial pH 6-7, and fermentation temperature 30 ℃. The ethanol concentration was 88g/kg in 18 h. After that, rapid ethanol production from cassava in SSF by Zymomonas mobilis 232B was studied. Through a series of experiments aided by Full Factorial Design and steepest ascent search, the optimal concentration yeast extract and ammonium sulfate were determined: 4 g/kg and 0.8 g/kg, each. Under optimum medium conditions, the optimal hydromodulus of cassava to water and glucoamylase dosages were obtained: hydromodulus of cassava to water at 1:3 and glucoamylase dosages 4 AGU/g starch. The ethanol production reached 4.915 g/kg/h. The residual sugar was analyzed by HPLC, and proved that the residual reducing sugar was some unfermentable oligosaccharide，but the components were more complex than that fermentation by Saccharomyces cerevisiae.

Spontaneous formation of two-dimensional gold networks at the air-water interface and their application in surface-enhanced Raman scattering (SERS)

Two-dimensional (2-D) gold networks were spontaneously formed at the air-water interface after HAuCl4 reacted with fructose at 90 degrees C in a sealed vessel, in a reaction in which fructose acted as both a reducing and a protecting agent. Through fine-tuning of the molar ratio of HAuCl4 to fructose, the thus-formed 2-D gold networks can be changed from a coalesced pattern to an interconnected pattern. In the coalesced pattern, some well-defined single-crystalline gold plates at the micrometer-scale could be seen, while in the interconnected pattern, many sub-micrometer particles and some irregular gold plates instead of well-defined gold plates appeared. It is also found that the 2-D gold networks in the form of an interconnected pattern can be used as substrates for surface-enhanced Raman scattering (SERS) because of the strong localized electromagnetic field produced by the gaps between the neighboring particles in the 2-D gold networks.

Capacitive detection of glucose using molecularly imprinted polymers

A novel glucose biosensor based on capacitive detection has been developed using molecularly imprinted polymers. The sensitive layer was prepared by electropolymerization of o-phenylenediamine on a gold electrode in the presence of the template (glucose). Cyclic voltammetry and capacitive measurements monitored the process of electropolymerization. Surface uncovered areas were plugged with 1-dodecanethiol to make the layer dense, and the insulating properties of the layer were studied in the presence of redox couples. The template molecules and the nonbound thiol were removed from the modified electrode surface by washing with distilled water. A capacitance decrease could be obtained after injection of glucose. The electrode constructed similarly but with ascorbic acid or fructose only showed a small response compared with glucose. The stability and reproducibility of the biosensor were also investigated. (C) 2001 Elsevier Science B.V. All rights reserved.

PROPERTIES OF BETA-CARBOXYETHYL-GERMANIUM SESQUIOXIDE AND INTERACTIONS OF IT WITH SOME SUBSTRATES

Three samples of β-carboxyethyl-germanium sesquioxide (Ge-132) have been prepared with different methods. Their IR, Raman, XPS, TG-DTA and FAB-MS spectra are quite different and indicate that they have different degree of polymerization and molecule structures. In the aqeous solution, all of them interaot strongly with fructose, but not with polypeptides such as GSH and GSSG. This faot may be important in understanding the bioactivity of Ge-132.

Fermentative hydrogen production by the new marine Pantoea agglomerans isolated from the mangrove sludge

A new fermentative hydrogen-producing bacterium was isolated from mangrove sludge and identified as Pantoea agglomerans using light microscopic examination, Biolog test and 16S rRNA gene sequence analysis. The isolated bacterium, designated as P. agglomerans BH-18, is a new strain that has never been optimized as a potential hydrogen-producing bacterium. In this study, the culture conditions and the hydrogen-producing ability of P. agglomerans BH-18 were examined. The strain was a salt-tolerant facultative anaerobe with the initial optimum pH value at 8.0-9.0 and temperature at 30 degrees C on cell growth. During fermentation, hydrogen started to evolve when cell growth entered late-exponential phase and was mainly produced in the stationary phase. The strain was able to produce hydrogen over a wide range of initial pH from 5 to 10, with an optimum initial pH of 6. The level of hydrogen production was affected by the initial glucose concentration, and the optimum value was found to be 10 g glucose/l. The maximum hydrogen-producing yield (2246 ml/l) and overall hydrogen production rate (160 ml/l/h) were obtained at an initial glucose concentration of 10 g/l and an initial pH value of 7.2 in marine culture conditions. In particular, the level of hydrogen production was also affected by the salt concentration. Hydrogen production reached a higher level in fresh culture conditions than in marine ones. In marine conditions, hydrogen productivity was 108 ml/l/h at an initial glucose concentration of 20 g/l and pH value of 7.2, whereas, it increased by 27% in fresh conditions. In addition, this strain could produce hydrogen using glucose and many other carbon sources such as fructose, sucrose, sorbitol and so on. As a result, it is possible that P. agglomerans BH-18 is used for biohydrogen production and biological treatment of mariculture wastewater and marine organic waste. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.