通过平衡透析研究嗜热脂肪芽孢杆菌延伸因子Tu与核苷酸和金属离子的结合。

The binding of nucleotides and metal ions to elongation factor Tu from Bacillus stearothermophilus as studied by equilibrium dialysis.

作者信息

Antonsson B, Kalbitzer H R, Wittinghofer A

出版信息

Hoppe Seylers Z Physiol Chem. 1981 Jun;362(6):735-43. doi: 10.1515/bchm2.1981.362.1.735.

DOI:10.1515/bchm2.1981.362.1.735

Abstract

EF-Tu from B. stearothermophilus binds divalent metal ions even in the absence of guanine nucleotides. The association constants necessary for characterizing the multiple equilibria between EF-Tu, GDP and the divalent ions magnesium and manganese were determined by equilibrium dialysis. The constants are 4.6 X 10(4) M-1 and 5.4 X 10(5) M-1 for the binding of Mg2 and 1.0 X 10(5) M-1 and 1.1 X 10(6) M-1 for the binding of Mn2 to EF-Tu and EF-Tu . GDP, respectively. In the absence of divalent ions EF-Tu binds GMP, GDP and GTP with association constants of 3 x 10(3) M-1, 1.7 x 10(7) M-1 and 1.3 x 10(6) M-1, respectively. The binding of GDP in the presence of metal ions is an order of magnitude stronger than in the absence of metal ions.

摘要

嗜热栖热菌的EF-Tu即使在没有鸟嘌呤核苷酸的情况下也能结合二价金属离子。通过平衡透析法测定了表征EF-Tu、GDP与二价离子镁和锰之间多重平衡所需的缔合常数。Mg2+与EF-Tu结合的常数分别为4.6×10⁴ M⁻¹和5.4×10⁵ M⁻¹，Mn2+与EF-Tu和EF-Tu·GDP结合的常数分别为1.0×10⁵ M⁻¹和1.1×10⁶ M⁻¹。在没有二价离子的情况下，EF-Tu与GMP、GDP和GTP结合的缔合常数分别为3×10³ M⁻¹、1.7×10⁷ M⁻¹和1.3×10⁶ M⁻¹。在有金属离子存在的情况下，GDP的结合比没有金属离子时强一个数量级。