用STM证实质粒pUC18DNA分子新构象的存在(英文)

VERIFICATION OF A NEW KIND CONFORMATION OF PLASMID pUC18 DNA MOLECULAR WITH SCANNING TUNNELING MICROSCOPE

用清亮裂解液法从大肠杆菌HB101细胞制备出的多拷贝质粒PUC18DNA分子的构象具有复杂的多样性，我们在对其进行STM研究时，证实了一种不同于已知构象（线性、松弛环型、互缠式超螺旋和线图型超螺旋）的新构象的存在．这种特殊构象呈紧密圆环形，其生化特性及生物学意义还有待进一步研究．

The multiple-copy plasmid pUC18 DNA which are isolated from Escherichia coli HB101 with the clear lystate method can form a variety of conformational isomers related to topological state in solution. When these samples are researched with the STM, the existence of a new conformation of plasmid pUC18 DNA molecular which is not same as those have been known (such as linear DNA, relaxed circular DNA, solenoidally supercoiled DNA and plectonemically supercoiled DNA) is verified. This new conformation looks like a ring coiling tightIy. Its specific property of biochemistry and molecular biology need to be futher studied.