Thompson R C, Dix D B, Eccleston J F
J Biol Chem. 1980 Dec 10;255(23):11088-90.
The rates of GTP hydrolysis and peptide formation during the reaction of Phe-tRNA . elongation factor Tu . GTP complex with acetyl-Phe-tRNA polyuridylate-programmed ribosomes have been measured. The GTPase reaction is second-order up to reactant concentrations of 0.2 microM and has a rate constant of 5 X 10(6) M-1 s-1 at 5 degrees C and 5 mM Mg2+, pH 7.2. The formation of peptide shows a lag phase and has a rate constant of 0.4 S-1 under these conditions. The results of a series of experiments between 5 degrees C and 25 degrees C show that GTP hydrolysis and peptide formation have Arrhenius activation energies of 13.1 and 15.3 kcal mol-1, respectively. The results indicate that these reactions proceed in vitro at rates comparable to those observed for protein biosynthesis in vivo, and that peptide bond formation occurs after GTP hydrolysis.
已测定了苯丙氨酰 - tRNA·延伸因子Tu·GTP复合物与乙酰苯丙氨酰 - tRNA聚尿苷酸编程核糖体反应过程中GTP水解和肽形成的速率。在反应物浓度达0.2微摩尔时，GTP酶反应为二级反应，在5℃、5毫摩尔镁离子、pH值7.2条件下，其速率常数为5×10⁶ M⁻¹ s⁻¹。肽的形成呈现一个延迟期，在此条件下其速率常数为0.4 S⁻¹。在5℃至25℃之间进行的一系列实验结果表明，GTP水解和肽形成的阿仑尼乌斯活化能分别为13.1千卡/摩尔和15.3千卡/摩尔。结果表明，这些反应在体外的进行速率与体内蛋白质生物合成所观察到的速率相当，并且肽键形成发生在GTP水解之后。
