为探究不同pH值对木瓜蛋白酶活性的影响及分子机制,采用分子模拟和荧光光谱分析等技术,对不同pH值条件下(4、5、6、7、8)木瓜蛋白酶的酶活性、均方根误差(root mean square deviation,RMSD)、蛋白质残基的波动、回旋半径、蛋白间氢键、...为探究不同pH值对木瓜蛋白酶活性的影响及分子机制,采用分子模拟和荧光光谱分析等技术,对不同pH值条件下(4、5、6、7、8)木瓜蛋白酶的酶活性、均方根误差(root mean square deviation,RMSD)、蛋白质残基的波动、回旋半径、蛋白间氢键、蛋白质二级结构和溶剂可及表面积等进行分析。结果表明:pH7时木瓜蛋白酶活性最高,pH4和pH8时比pH7时活性分别降低约5.00%和5.35%;分子模拟结果显示,不同pH值下木瓜蛋白酶的回旋半径波动不大,pH8时RMSD有较大波动;pH4和pH8时蛋白酶活性中心的3个氨基酸残基有较大波动;随着pH值的增加,木瓜蛋白酶间氢键数量逐渐增加,但pH8的氢键数量较pH7下降3.4个;pH7条件下木瓜蛋白酶活性中心与底物结合紧密,酶蛋白内部结构更致密,而pH4条件下酶活性中心与底物结合部位缝隙较大,酶蛋白内部结构疏松;pH4和8时活性下降与该条件下木瓜蛋白酶的结构变化有关,如氢键的破坏、活性中心残基的波动、疏水表面积的改变、β-折叠等二级结构的变化等。本研究从分子模拟角度明确了pH值对木瓜蛋白酶活性的影响。展开更多
The feasibility of the mercaptopropyl acid modified CdTe nanoparticles synthesized in aqueous solution to the labeling of biomoleculespapain via electrostatic interaction was studied in this paper. The absorption spec...The feasibility of the mercaptopropyl acid modified CdTe nanoparticles synthesized in aqueous solution to the labeling of biomoleculespapain via electrostatic interaction was studied in this paper. The absorption spectrum of CdTe papain solution became more flat than that of CdTe nanoparticles in the wavelength range from 400 to 600 nm. While the emission peak of CdTe papain solution underwent a red shift, the intrinsic emission band width was unchanged. The TEM images of monodisperse mercaptopropyl acid stabilized CdTe nanoparticles and CdTe papain solution were compared and the effect of pH of buffer solution was studied. It was proved that the red shift of the emission peak was the result of the electrostatic interaction between CdTe nanoparticles and papain.展开更多
文摘为探究不同pH值对木瓜蛋白酶活性的影响及分子机制,采用分子模拟和荧光光谱分析等技术,对不同pH值条件下(4、5、6、7、8)木瓜蛋白酶的酶活性、均方根误差(root mean square deviation,RMSD)、蛋白质残基的波动、回旋半径、蛋白间氢键、蛋白质二级结构和溶剂可及表面积等进行分析。结果表明:pH7时木瓜蛋白酶活性最高,pH4和pH8时比pH7时活性分别降低约5.00%和5.35%;分子模拟结果显示,不同pH值下木瓜蛋白酶的回旋半径波动不大,pH8时RMSD有较大波动;pH4和pH8时蛋白酶活性中心的3个氨基酸残基有较大波动;随着pH值的增加,木瓜蛋白酶间氢键数量逐渐增加,但pH8的氢键数量较pH7下降3.4个;pH7条件下木瓜蛋白酶活性中心与底物结合紧密,酶蛋白内部结构更致密,而pH4条件下酶活性中心与底物结合部位缝隙较大,酶蛋白内部结构疏松;pH4和8时活性下降与该条件下木瓜蛋白酶的结构变化有关,如氢键的破坏、活性中心残基的波动、疏水表面积的改变、β-折叠等二级结构的变化等。本研究从分子模拟角度明确了pH值对木瓜蛋白酶活性的影响。
文摘The feasibility of the mercaptopropyl acid modified CdTe nanoparticles synthesized in aqueous solution to the labeling of biomoleculespapain via electrostatic interaction was studied in this paper. The absorption spectrum of CdTe papain solution became more flat than that of CdTe nanoparticles in the wavelength range from 400 to 600 nm. While the emission peak of CdTe papain solution underwent a red shift, the intrinsic emission band width was unchanged. The TEM images of monodisperse mercaptopropyl acid stabilized CdTe nanoparticles and CdTe papain solution were compared and the effect of pH of buffer solution was studied. It was proved that the red shift of the emission peak was the result of the electrostatic interaction between CdTe nanoparticles and papain.
