MAGNESIUM-ION DEPENDENT EQUILIBRIA, KINETICS, AND THERMODYNAMIC PARAMETERS OF ARTEMIA RIBOSOME DISSOCIATION AND SUBUNIT ASSOCIATION
MAGNESIUM-ION DEPENDENT EQUILIBRIA, KINETICS, AND THERMODYNAMIC PARAMETERS OF ARTEMIA RIBOSOME DISSOCIATION AND SUBUNIT ASSOCIATION
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DOI：
10.1021/bi00360a032
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发表时间：
1986-06-17
期刊：
影响因子：
2.9
通讯作者：
HARRIGAN, T
中科院分区：
文献类型：
--
作者：
GOSS, DJ;HARRIGAN, T
用激光光散射法研究了镁离子浓度对卤虫核糖体解离和亚基结合的平衡和动力学的影响。发现添加0.1-0.05 mM的亚精胺和100 mM的KCl可降低核糖体聚集。核糖体在低[Mg~(2+)]下是稳定的，核糖体-亚基平衡曲线与镁离子滴定的方向和来源无关。热力学参数由温度相关的平衡得到，并与小麦胚芽和大肠杆菌A型核糖体的热力学参数进行了比较。对于40s和60s亚基的缔合计算的熵项很小，反应是放热的。熵项为负值，有利于亚单位解离，对自由能的贡献小于焓项。测定了核糖体解离和亚基结合的速率常数。反应曲线没有提供顺序过程的证据，而且是均匀的。
The influence of magnesium ion concentration on the equilibrium and kinetics of Artemia ribosome dissociation and subunit association has been studied by laser light scattering. Ribosomal aggregation was found to be reduced by additon of 0.1-0.05 mM spermidine and KCl concentrations of 100 mM. The ribosomes were found to be stable at low [Mg2+], and the curves obtained for ribosome-subunit equilibrium were independent of the direction and origin of the magnesium ion titration. Thermodynamic parameters were obtained from the temperature-dependent equilibria and have been compared to those of wheat germ and Escherichia coli type A ribosomes. The entropy term calculated for the association of 40S and 60S subunits is small, and the reaction is exothermic. The entropy term is negative, favoring subunit dissociation, and contributes less to the free energy than the enthalpy term. Rate constants for ribosome dissociation and subunit association have been determined. The reaction curves gave no evidence for sequential processes and were homogeneous.