Ganesan A K
Proc Natl Acad Sci U S A. 1973 Oct;70(10):2753-6. doi: 10.1073/pnas.70.10.2753.
Cells of Escherichia coli treated with lysozyme and Brij-58 become permeable to proteins, but do not release their DNA. I incubated permeable cells with an endonuclease that produces single-strand breaks in DNA-containing pyrimidine dimers. The enzyme entered the permeable cells, and, if they had been irradiated with ultraviolet light, caused breaks in their DNA. The frequency of breaks was estimated from the sedimentation pattern of the DNA in alkaline sucrose gradients. The procedure is sensitive enough to detect the dimers produced by a dose of 10 erg/mm(2) at 254 nm, or about 50 dimers per E. coli genome. This method exemplifies and extends the use of permeabilized cells for examining biological processes at the molecular level.
用溶菌酶和Brij - 58处理的大肠杆菌细胞对蛋白质具有通透性,但不会释放其DNA。我将通透细胞与一种能在含嘧啶二聚体的DNA中产生单链断裂的核酸内切酶一起孵育。该酶进入通透细胞,并且,如果这些细胞已用紫外线照射过,就会导致其DNA断裂。通过碱性蔗糖梯度中DNA的沉降模式来估计断裂频率。该方法灵敏度足以检测在254nm下10尔格/平方毫米剂量产生的二聚体,或大约每大肠杆菌基因组50个二聚体。这种方法例证并扩展了利用通透细胞在分子水平上研究生物学过程的应用。