Goss D J, Harrigan T
Biochemistry. 1986 Jun 17;25(12):3690-5. doi: 10.1021/bi00360a032.
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 addition 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.
通过激光散射研究了镁离子浓度对卤虫核糖体解离和亚基缔合的平衡及动力学的影响。发现添加0.1 - 0.05 mM亚精胺和100 mM的KCl浓度可减少核糖体聚集。核糖体在低[Mg2+]浓度下是稳定的，并且核糖体 - 亚基平衡所得到的曲线与镁离子滴定的方向和起始点无关。从温度依赖性平衡获得了热力学参数，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。计算得出的40S和60S亚基缔合的熵项较小，且该反应是放热的。熵项为负，有利于亚基解离，并且对自由能的贡献小于焓项。已确定核糖体解离和亚基缔合的速率常数。反应曲线没有显示出连续过程的证据，并且是均相的。
