DNA分子结构的多态性研究(Ⅲ)——生物大分子探针吖啶橙诱导λ┐DNA由线型向环型的转变

The Investigation of the Various Structures of DNA Molecules(Ⅲ) The Coil toroid Transition of λ DNA Induced by the Biomolecular Probe AO

病毒和细胞体内的ＤＮＡ是以高度紧密的凝聚态存在的．自从在体外发现亚精胺、精胺可诱导无规卷曲的ＤＮＡ形成有序、独特的凝聚结构形态以来，许多学者深入研究了多价阳离子的诱导特性，以期阐明ＤＮＡ在病毒内的组装和染色体中凝聚作用的机制［１，２］．由于多价阳离子...

The helix and structure transition of λ DNA in AO solutions were investigated by SEM and AFM methods. Using SEM, we observed the turn and globular as well as toroidal condensates of λ DNA induced by AO. The fine structures of these condensates were further observed by using AFM. Our results reveal that the mechanism of the coil toroid transition of λ DNA resulted from the changed environment is related to the shrinking and collapsing process as well as the self assembling process of these condensates.