Blumberg B M, Nakamoto T, Kézdy F J
Proc Natl Acad Sci U S A. 1979 Jan;76(1):251-5. doi: 10.1073/pnas.76.1.251.
The 30S initiation complex, formed with the 30S ribosomal subunit, mRNA, and fMet-tRNA, has been shown by kinetic analysis with limiting concentrations of Escherichia coli ribosomes to be an obligatory intermediate in the formation of the 70S initiation complex. The formation of the 70S initiation complex began with an induction period and was proportional to the concentration of the 30S complex, which rapidly rose to a peak. The entire time course of the sequential pseudo-first-order, second-order reaction was reproduced accurately by the overall rate expression, in which we used rate constants that were determined by carrying out 30S and 70S complex formation separately. By using limiting concentrations of mRNA, we showed that phage MS2 RNA contained no specific signal that enhanced its rate of 30S complex formation with E. coli ribosomes and initiation factors; the pseudo-first-order rate constants obtained with poly(A3C9G1U1), poly(C15G1U4), and poly(G1U3) were 12-45 times higher than that with MS2 RNA. The observation that the rate constants for binding of fMet-tRNA and AcPhe-tRNA with a given synthetic RNA were comparable indicated that the initiator codon is recognized only indirectly through the initiator tRNA.
通过对大肠杆菌核糖体的极限浓度进行动力学分析表明，由30S核糖体亚基、mRNA和fMet - tRNA形成的30S起始复合物是70S起始复合物形成过程中的一个必经中间体。70S起始复合物的形成始于一个诱导期，且与30S复合物的浓度成正比，30S复合物的浓度迅速上升至峰值。通过总体速率表达式能够准确再现连续的准一级、二级反应的整个时间进程，在该表达式中，我们使用了分别通过进行30S和70S复合物形成所确定的速率常数。通过使用mRNA的极限浓度，我们表明噬菌体MS2 RNA不包含能提高其与大肠杆菌核糖体和起始因子形成30S复合物速率的特定信号；用聚（A3C9G1U1）、聚（C15G1U4）和聚（G1U3）获得的准一级速率常数比用MS2 RNA获得的高12 - 45倍。关于fMet - tRNA和AcPhe - tRNA与给定合成RNA结合的速率常数具有可比性的观察结果表明，起始密码子仅通过起始tRNA间接被识别。
