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PPL-catalyzed synthesis of the precursor dipeptides of RGD as a cellular adhesion factor, Benzyl-Arg-Gly-NH2 and CBZ-Gly-Asp-NH2, was conducted in water-organic cosolvents systems. Five water-miscible organic solvents, which have some advantage over the water-immiscible organic solvent systems or the anhydrous organic solvent systems used often in protease-catalyzed synthesis of a peptide bond, were tested. The reaction condition of PPL-catalyzed synthesis of the dipeptides was optimized by examining the main factors affecting the product yield. The optimal reaction condition for the synthesis of Benzyl-Arg-Gly-NH2 was set up as pH 8.0, 15 degrees C in 40% MeOH for 10 h with the maximum yield of 73.6%. The optimum condition for the synthesis of CBZ-Gly-Asp-NH2 was pH 7.0, 15 degrees C in 50% MeOH for 10h with the maximum yield of 67.0%.  相似文献
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Sucrose: sucrose 1-fructosyltransferase (1-SST) cDNA from Lactuca sativa, coding the enzyme responsible for lower degree polymers fructan biosynthesis, was cloned by RT-PCR and RACE methods. The 1-SST cDNA under the control of CaMV 35S promoter was introduced into tobacco by Agrobacterium-mediated leaf disc transformation protocol. Fructan synthesis in vitro and carbohydrate analysis showed that sense transgenic tobacco plant displayed sucrose: sucrose 1-fructosyltransferse activity. After freezing stress, significant increases in electrolyte leakage and malondialdehyde were found in the wild type and anti-sense transgenic plants, while no apparent differences were observed in sense transgenic plants. Meanwhile, water soluble carbohydrate, fructan and fructose of sense transgenic plants remarkably increased, compared with those of wild type and anti-sense plants. No significant difference was detected in superoxide dismutase activity between transgenic and wild type plants. The above results demonstrated that the expression of 1-SST gene improved the freezing resistance of transgenic tobacco plants.  相似文献
3.
棕榈科植物在园林上的应用已形成多种类型的植物景观。本文运用BIB-LCJ审美评判法评价七种类型的棕榈科植物景观,研究公众对各种棕榈科植物景观的审美趋向,从而讨论如何配置棕榈科植物来营造符合公众审美的植物景观。  相似文献
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