THERMODYNAMIC AND KINETIC STUDIES ON INTERCONVERSION BETWEEN LINEAR AND CIRCULAR FORMS OF PHAGE LAMBDA DNA
THERMODYNAMIC AND KINETIC STUDIES ON INTERCONVERSION BETWEEN LINEAR AND CIRCULAR FORMS OF PHAGE LAMBDA DNA
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DOI：
10.1016/s0022-2836(66)80213-9
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发表时间：
1966-01-01
影响因子：
5.6
通讯作者：
DAVIDSON, N
中科院分区：
文献类型：
--
作者：
WANG, JC;DAVIDSON, N
线性和环状单体形式的[λ] b2b 5c DNA之间的平衡已被测量为温度在0.10 M-NaCl，0-01 M-Na 3EDTA（pH 7.3）和2.0 M-NaCl，0.01 M-Na 3EDTA（pH 7.3）中的函数。从两侧接近平衡;条带沉降用于测量两种形式的量。在0.13 M-Na+中，[DELTA]H = - 91（[正负]10）kcal。摩尔-1，[Δ] S =-280（[±]30）eu;在2 M-Na+中，[Δ] H =-85（[±]10）和[Δ] S =-250（[±]30）。在两种介质中，转变的中点发生在50-6和63-6[degree]C。根据这些数据，环化中涉及的碱基对的数目估计为10[±]1。一阶弛豫的系统平衡的速率常数已被测量。这些结果表明，环化反应的速率不是由两端相互扩散的速率控制的，而是由氢键形成的速率控制的。环化反应的活化能约为23千卡。摩尔-1。方程log 10 k（min-1）= [长划线] 5.2 x 103/T + 14.9（2.0 M-Na+）和log 10 k（min-1）= - 5.0 x 103/T + 13.6（0.13 M-Na+）可分别用于估计55和47[degree]C以下的成圈率。
The equilibrium between the linear and the cyclic monomer forms of [lambda] b2b5c DNA has been measured as a function of temperature in 0.10 M-NaCI, 0-01 M-Na3EDTA (pH 7.3) and in 2.0 M-NaCl, 0.01 M-Na3EDTA (pH 7.3). Equilibrium was approached from both sides; band sedimentation was used to measure the amounts of the two forms. In 0.13 M-Na+,[DELTA]H = - 91 ([plus or minus]10) kcal. mole-l, [DELTA] S = - 280 ([plus or minus]30) eu; in 2 M-Na+, [DELTA] H = - 85 ([plus or minus]10) and [DELTA] S = - 250 ([plus or minus]30). The midpoints of the transitions occur at 50-6 and 63-6[degree]C in the two media. From these data, the number of base pairs involved in cyclization is estimated as 10[plus or minus]1. Rate constants for the first-order relaxation of the system to equilibrium have been measured. These results indicate that the rate of cyclization is not controlled by the rate of diffusion of the two ends toward each other but rather by the rate of hydrogen-bond formation. The activation energy for the cyclization process is about 23 kcal. mole-1. The equations, log10k (min-1) = [long dash] 5.2 x 103/T + 14.9 (2.0 M-Na+) and log10k(min-1) = - 5.0 x 103/T + 13.6 (0.13 M-Na+) can be used to estimate the rate of circle formation below 55 and 47[degree]C, respectively.