Saunders C W, Guild W R
Mol Gen Genet. 1981;181(1):57-62. doi: 10.1007/BF00339005.
The covalently closed (CC) monomer form of plasmid pMV158 was found to transform pneumococcus (Streptococcus pneumoniae) and to do so with two-hit kinetics. The evidence came from analysis of the behavior of the transforming activity in fractions from preparative gel electrophoresis. Activity in the first major peak to elute (i) co-eluted with monomer CC as detected on analytical gels, (ii) banded as CC in dye-buoyancy gradients, (iii) sedimented with the velocity expected for monomer CC, and (iv) gave two-hit kinetics as functions of both concentration and time of exposure of the cells to DNA. A second major peak of activity behaved physically as though mostly due to dimer CC forms and gave single-hit response curves. Because almost no dimer was detectable optically on analytical gels of starting preparations, its specific activity was high relative to that of the monomers.
发现质粒pMV158的共价闭合（CC）单体形式可转化肺炎球菌（肺炎链球菌），且转化过程呈现双 hit 动力学。证据来自对制备性凝胶电泳各组分中转化活性行为的分析。第一个洗脱的主要峰中的活性：（i）在分析凝胶上检测时与单体CC共洗脱；（ii）在染料浮力梯度中呈CC条带；（iii）以单体CC预期的速度沉降；（iv）作为细胞暴露于DNA的浓度和时间的函数呈现双 hit 动力学。第二个主要活性峰在物理行为上似乎主要归因于二聚体CC形式，并给出单 hit 响应曲线。由于在起始制剂的分析凝胶上几乎检测不到二聚体，其比活性相对于单体较高。
