Jakes R, Fersht A R
Biochemistry. 1975 Jul 29;14(15):3344-50. doi: 10.1021/bi00686a009.
The tyrosyl-tRNA synthetase from Escherichia coli binds only 1 mol of tRNA, tyrosine, and tyrosyl adenylate per mol of enzyme dimer. However, like the enzyme from Bacillus stearothermophilus, once one active site is occupied by tyrosyl adenylate the other becomes accessible to bind a further molecule each of tyrosine and ATP. Both bacterial enzymes show biphasic kinetics with respect to tyrosine in the aminoacylation of tRNA. Equilibrium dialysis experiments show that this is due to 2 mol of tyrosine binding in the presence of ATP and tRNA. A method is given for a correction for the effects of hydrolysis of the charged tRNA on the aminoacylation kinetics.
来自大肠杆菌的酪氨酰 - tRNA合成酶每摩尔酶二聚体仅结合1摩尔的tRNA、酪氨酸和酪氨酰腺苷酸。然而，与嗜热脂肪芽孢杆菌的酶一样，一旦一个活性位点被酪氨酰腺苷酸占据，另一个活性位点就可结合酪氨酸和ATP的另外一个分子。两种细菌酶在tRNA的氨酰化反应中对酪氨酸均表现出双相动力学。平衡透析实验表明，这是由于在ATP和tRNA存在的情况下有2摩尔酪氨酸结合。文中给出了一种校正带电荷tRNA水解对氨酰化动力学影响的方法。
