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排序方式: 共有94条查询结果,搜索用时 15 毫秒
31.
Qiang Wang Liuliu Su Xuerong Fan Jiugang Yuan Li Cui Ping Wang 《Fibers and Polymers》2009,10(3):333-337
Two types of lipases, L3126 and Lipex 100L, were used to modify the surface of poly(lactic acid) (PLA) fiber by measuring
weight loss percentage and wettability of the fiber in this work. The influence factors were discussed and optimized based
on single-factor experiments. The optimal conditions for the modification of poly(lactic acid) fiber with lipases were determined
as follows: incubation with lipase L3126 of 0.5 g/l at 45 °C and pH 8.5 for 8 hours and incubation with lipase of 10 ml/l at 40 °C and pH 7.5 for 10 hours. Lipase L3126 showed higher biodegradation ability to poly(lactic acid) fiber than lipase
Lipex 100L. The scanning electron microscopy confirmed that both of the two lipases could lead to the formation of etching
characters on treated poly(lactic acid) fibers in comparison with the blank samples. Furthermore, the wettability of the fibers
treated with the lipases was evidently improved, especially Lipase L3126. 相似文献
32.
研究了脂肪酶处理的最佳工艺条件及脂肪酶处理对麦秸纤维表面性能的影响.结果表明,最佳工艺条件为:处理温度50℃,时间12h,pH值7.5,酶用量20g/L.借助扫描电子显微镜和傅立叶红外光谱分析技术,利用酶处理过的麦秸纤维,观察其微观结构和表面官能团的变化,发现经过酶处理的麦秸纤维表面粗糙,蜡质层部分脱落和翘起;3300cm-1处的羟基(-OH)峰增加,有利于提高其胶合性能. 相似文献
33.
铜绿假单胞菌脂肪酶Lipase基因的原核表达(英文) 总被引:4,自引:1,他引:3
[Objective] The aim of this study was to investigate the prokaryotic expression of pseudomonas aeruginosa Lipase gene.[Method]Lipase gene was amplified by PCR from the genome DNA of pseudomonas aeruginosa,and its nucleotide sequence was determined.The prokaryotic expression vector of Lipase gene was constructed by the gene recombination technique.The protein expression was induced for 4 hours by IPTG with the final concentration of 1.0 mmol/L,and then SDS-PAGE electrophoresis was analyzed.[Result]The sequence of mature peptides in Lipase gene cloned from pseudomonas aeruginosa had a 99.36% homology with that of pseudomonas aeruginosa lipase submitted in NCBI,so the prokaryotic expression vector of Lipase gene pET32a-Lip was successfully constructed.Furthermore,the results of SDS-PAGE electrophoresis showed that the target gene was expressed highly and effectively.[Conclusion]The cloned pseudomonas aeruginosa lipase with its signal peptide could be normally expressed in E.coli and also used for further study. 相似文献
34.
Vasudeva Kamath 《Pesticide biochemistry and physiology》2008,90(1):58-65
The significant antiradical activity of cashew skin extract was previously described. In this investigation, the extent of protection offered by cashew nut skin extract (CSE) against the damage induced in rat pancreas by sub chronic doses dimethoate (DM), an organophosphorous pesticide was studied. Rats were supplemented with CSE at 20 mg/kg b.w./d after a daily dose of DM at 40 mg/kg/d b.w. for 2 months. Weekly random blood glucose, oral glucose tolerance test (OGTT); pancreatic damage markers like amylase and lipase; oxidative damage markers such as reactive oxygen species generated, extent of lipid peroxidation, host antioxidant defenses like reduced glutathione (GSH); GSH-dependent enzyme activities viz., glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR); free radical scavenger enzymes viz., catalase and superoxide dismutase (SOD); xenobiotic metabolizing enzymes like DT-diaphorase and NADPH-diaphorase were measured in the four different groups namely (1) control, (2) DM treated, (3) CSE supplemented, (4) CSE supplements following DM treatment. Random blood glucose levels increased significantly on exposure to DM compared to that in control rats (119 ± 5 mg/dl vs. 92 ± 4 mg/dl), while the blood glucose levels in CSE supplemented rats were comparable to that of controls. DM treated rats exhibited impaired glucose tolerance at the end of two months as indicated by OGTT, while DM treated rats with CSE supplements showed normal glucose tolerance. Pancreatic specific marker enzymes like amylase and lipase in serum were restored to normalcy in rats supplemented with CSE following treatment with DM which otherwise was increased in the DM treated rats. Distinctly lower levels of GSH, increased levels of ROS, higher extent of lipid peroxidation, along with alterations in antioxidant enzymes and increase in xenobiotic metabolizing enzymes were evident in pancreas of DM treated rats. However, CSE supplement ameliorated the biochemical alterations in the pancreatic milieu in DM treated rats. Treatment with CSE significantly protected rat pancreas from injury, thus ameliorating and restoring tissue antioxidant status and also conferring normal glucose tolerance. The active components present in cashew skin extract can perhaps be effective in reducing the extent of pancreatic injury and in overcoming tissue damage caused by exposure to dimethoate. 相似文献
35.
脂肪酶法制备生物柴油进展 总被引:1,自引:0,他引:1
脂肪酶催化法制备生物柴油具有反应条件温和,操作简单,环境友好等优点。综述了脂肪酶的选择,比较了游离酶与固定化酶的特点,分析了影响酶催化效率的因素。尤其对离子液体体系以及纳米粒子技术在生物柴油制备中的最新进展进行了相应介绍。 相似文献
36.
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The effect of two lipases and DATEM at different concentrations on the rheological and thermal properties of white and whole wheat flour doughs was determined by farinograph, extensograph, texture analyzer and differential scanning calorimetry. Lipases provided similar or better results than that of DATEM on decreasing softening degree and stickiness, and increasing stability, maximum resistance to extension and hardness. Extensibility and energy did not change with lipases, but decreased with DATEM. Lipases and DATEM slightly modified the transition temperatures and enthalpies of ice-melting and starch gelatinization, but significantly increased the moisture and unfrozen water contents, and decreased the solid concentration in unfrozen water. The greatest effect of lipases was observed on decreasing the peak temperature and increasing the enthalpy of amylose–lipid complex dissociation. The changes in the rheological and thermal properties were almost independent of the concentration levels tested, and were mostly reduced when whole wheat flour was used. The improvement in the dough properties by lipases is possibly related to the in situ formation of surface active compounds from endogenous flour lipids. Presumably, these compounds are already located in the right positions in dough, where they might have higher interaction potentials than DATEM with the dough components. 相似文献
39.
40.
固定化酶催化桐油酯交换反应的研究 总被引:9,自引:0,他引:9
桐油与甲醇酯交换反应的产物主要为桐酸甲酯,该产物不仅可作为可再生的替代能源-生物柴油,同时是一种重要的化工原料。本文以桐籽油为原料,研究固定化脂肪酶催化桐油与甲醇酯交换反应的工艺条件,利用Novo435脂肪酶,在无有机溶剂存在的情况下,利用响应面研究方法,对桐油酯交换反应的工艺条件进行了研究和优化。得到了桐油酯交换反应的最佳工艺条件:醇油比2.2:1、温度43℃、脂肪酶用量14%(与油脂的质量比)、搅拌转速200rpm,反应18h后,桐油的酯交换率达到了67.5%(理论为73.3%)。脂肪酶经有机溶剂洗涤后连续使用120h,桐油酯交换率减小了6%。理论上甲醇与油脂的摩尔比为3:1,甲醇不能一次加入,分两批加入,共反应36h后,桐油的酯交换率达到85%。 相似文献