A Bowman-Birk inhibitor with activity against gut proteases of Helicoverpa armigera was extracted in 0.I M sodium phosphate buffer from defatted seed flour of Albizia lebbeck. It was purified to 29.62 folds with 51.43...A Bowman-Birk inhibitor with activity against gut proteases of Helicoverpa armigera was extracted in 0.I M sodium phosphate buffer from defatted seed flour of Albizia lebbeck. It was purified to 29.62 folds with 51.43% recovery using ammonium sulfate precipitation, gel filtration chromatography on Sephadex G-100 column and ion ex- change chromatography on DEAE-Sephadex As0. The purified protein had a molecular weight of 12,303 daltons as determined by SDS-PAGE. It was found to be heat stable up to 60~C and had two pH optima of 7.5 and 9.0. The inhibitor exhibited non-competitive pattern of inhibition with a low Ki value of 0.2 ~tM. The inhibitoi- was found to be susceptible to varying concentrations of reducing agents like DTT and 2- mercaptoethanol, thereby indicating the role of disulphide bridges in maintaining its three dimensional structure and stability. The purified inhibitor caused mortality and suppressed larval growth ofPieris brassi- cae larvae. It was also found to be effective against gut trypsin extracted from Spodoptera littoralis. The sequence of the genes encoding for such inhibitors can be determined and the genes expressing protease inhibitors can be used in vegetable crops to confer resistance against insect pests and other plant pathogens.展开更多
【目的】提高松茸粗多糖提取率,探究松茸多糖纯化组分及抗氧化作用。【方法】采用超声波辅助水提醇沉法提取松茸粗多糖,优化提取工艺,使用DEAE-Sepharose Fast Flow离子柱分离纯化粗多糖,采用离子色谱法分析单糖成分,并测定体外抗氧化...【目的】提高松茸粗多糖提取率,探究松茸多糖纯化组分及抗氧化作用。【方法】采用超声波辅助水提醇沉法提取松茸粗多糖,优化提取工艺,使用DEAE-Sepharose Fast Flow离子柱分离纯化粗多糖,采用离子色谱法分析单糖成分,并测定体外抗氧化活性。【结果】最优提取工艺参数为:浸提时间2.25 h,料液比1∶31(g∶mL),浸提温度83.50℃,该条件下多糖提取率为8.67%。松茸粗多糖经分离纯化后收集到3种多糖组分(TMP-1、TMP-2、TMP-3),主要由岩藻糖、盐酸氨基葡萄糖、半乳糖、葡萄糖和甘露糖组成,其中TMP-1存在鼠李糖,TMP-2和TMP-3存在葡萄糖醛酸。松茸粗多糖和3种纯化多糖组分均具有一定的抗氧化活性且存在量效关系,抗氧化能力强弱为:松茸粗多糖>TMP-2>TMP-3>TMP-1。【结论】松茸多糖有一定的抗氧化活性,且松茸粗多糖效果最好,分离纯化后的多糖组分抗氧化活性有所降低。本研究为松茸多糖的开发利用提供了理论基础,对其功能食品研发具有重要意义。展开更多
文摘A Bowman-Birk inhibitor with activity against gut proteases of Helicoverpa armigera was extracted in 0.I M sodium phosphate buffer from defatted seed flour of Albizia lebbeck. It was purified to 29.62 folds with 51.43% recovery using ammonium sulfate precipitation, gel filtration chromatography on Sephadex G-100 column and ion ex- change chromatography on DEAE-Sephadex As0. The purified protein had a molecular weight of 12,303 daltons as determined by SDS-PAGE. It was found to be heat stable up to 60~C and had two pH optima of 7.5 and 9.0. The inhibitor exhibited non-competitive pattern of inhibition with a low Ki value of 0.2 ~tM. The inhibitoi- was found to be susceptible to varying concentrations of reducing agents like DTT and 2- mercaptoethanol, thereby indicating the role of disulphide bridges in maintaining its three dimensional structure and stability. The purified inhibitor caused mortality and suppressed larval growth ofPieris brassi- cae larvae. It was also found to be effective against gut trypsin extracted from Spodoptera littoralis. The sequence of the genes encoding for such inhibitors can be determined and the genes expressing protease inhibitors can be used in vegetable crops to confer resistance against insect pests and other plant pathogens.
文摘【目的】提高松茸粗多糖提取率,探究松茸多糖纯化组分及抗氧化作用。【方法】采用超声波辅助水提醇沉法提取松茸粗多糖,优化提取工艺,使用DEAE-Sepharose Fast Flow离子柱分离纯化粗多糖,采用离子色谱法分析单糖成分,并测定体外抗氧化活性。【结果】最优提取工艺参数为:浸提时间2.25 h,料液比1∶31(g∶mL),浸提温度83.50℃,该条件下多糖提取率为8.67%。松茸粗多糖经分离纯化后收集到3种多糖组分(TMP-1、TMP-2、TMP-3),主要由岩藻糖、盐酸氨基葡萄糖、半乳糖、葡萄糖和甘露糖组成,其中TMP-1存在鼠李糖,TMP-2和TMP-3存在葡萄糖醛酸。松茸粗多糖和3种纯化多糖组分均具有一定的抗氧化活性且存在量效关系,抗氧化能力强弱为:松茸粗多糖>TMP-2>TMP-3>TMP-1。【结论】松茸多糖有一定的抗氧化活性,且松茸粗多糖效果最好,分离纯化后的多糖组分抗氧化活性有所降低。本研究为松茸多糖的开发利用提供了理论基础,对其功能食品研发具有重要意义。
