Date T
Eur J Biochem. 1979 May 2;96(1):167-75. doi: 10.1111/j.1432-1033.1979.tb13026.x.
The kinetics of the binding reaction of MS2 phage to free F pili, which were highly purified from Escherichia coli, has been studied using a membrane filter assay. The rate of dissociation (kd) of the MS2-phage--F-pilus complex is very slow and follows first-order kinetics with a half-life of 4.2 h at 30 degrees C in the standard buffer. The dissociation rate is rather insensitive to temperature, but becomes more rapid at high ionic strength or at basic pH. In a 0.25 M ionic strength buffer, the half-life of the complex is about 1.0 min. The rate of association is very fast and follows second-order kinetics with the rate constant for association (ka) being 8 x 10(7) M-1 s-1 at 30 degrees C in the standard buffer. The rate of association is almost insensitive to ionic strength but slightly sensitive to pH or temperature. Monovalent cations can also promote the binding reaction as well as divalent cations but the complex formed with monovalent cation is unstable. A study of the kinetics of dissociation suggests that there are two types of interaction between MS2 phage and F pilus; one is a strong interaction formed with divalent cations and the other is a weak one formed with monovalent cations. The physical nature of the bonds involved in the former and the latter seems to be mainly electrostatic and non-electrostatic respectively. The mechanism of the binding reaction is discussed.
利用膜过滤分析法研究了MS2噬菌体与从大肠杆菌中高度纯化的游离F菌毛结合反应的动力学。MS2噬菌体 - F菌毛复合物的解离速率（kd）非常缓慢，在标准缓冲液中于30℃下遵循一级动力学，半衰期为4.2小时。解离速率对温度相当不敏感，但在高离子强度或碱性pH下会变得更快。在0.25 M离子强度缓冲液中，复合物的半衰期约为1.0分钟。结合速率非常快，遵循二级动力学，在标准缓冲液中于30℃下结合速率常数（ka）为8×10⁷ M⁻¹ s⁻¹。结合速率几乎对离子强度不敏感，但对pH或温度略有敏感。单价阳离子以及二价阳离子也能促进结合反应，但与单价阳离子形成的复合物不稳定。对解离动力学的研究表明，MS2噬菌体与F菌毛之间存在两种相互作用；一种是与二价阳离子形成的强相互作用，另一种是与单价阳离子形成的弱相互作用。前者和后者所涉及的键的物理性质似乎分别主要是静电的和非静电的。讨论了结合反应的机制。
