Kinberg-Calhoun J, Wetmur J G
Biochemistry. 1981 Apr 28;20(9):2645-50. doi: 10.1021/bi00512a044.
The electron microscope was used to count the number of double-stranded linear and circular renaturation products of a 2:1 by weight mixture of restricted double-stranded linear phi X174 RFI and single-stranded circular phi X174 viral deoxyribonucleic acid (DNA). More linear molecules than circular molecules are observed. However, when a 1:1 mixture of aliquots of either phi X174 RFI or SV40 DNA, each previously cleaved with a different single-site restriction enzyme, is denatured and renatured under conditions which assure circularization with out of phase molecules, an equal number of linear and circular molecules is observed. These experiments indicate that the nucleation rate is not affected by circular permutation of linear strands but is decreased approximately 3-fold when one of the reacting strands is circular. An excluded volume theory is developed which is consistent with these as well as previous results concerning the effects of DNA strand lengths on renaturation rates.
使用电子显微镜对经限制性内切酶切割的双链线性φX174 RFI与单链环状φX174病毒脱氧核糖核酸（DNA）按重量比2:1混合后的双链线性和环状复性产物数量进行计数。观察到线性分子比环状分子多。然而，当将先前用不同单一位点限制性内切酶切割的φX174 RFI或SV40 DNA的等份样品按1:1混合，在确保异相分子环化的条件下进行变性和复性时，观察到线性分子和环状分子数量相等。这些实验表明，成核速率不受线性链的环状排列影响，但当反应链之一为环状时，成核速率大约降低3倍。提出了一种排除体积理论，该理论与这些结果以及先前关于DNA链长度对复性速率影响的结果一致。
