... Moreover, as the triple helix was not stable in the absence of inter-calator, it was possible to switch easily from conditionswhere the triple helix was very stable to conditionswhere it was totally ... the labelled fragment and the plasmid was observed.We were able to detect 250 attomol of plasmid withoutambiguity, and a band could be identified with as few as 50 attomol (Fig. 5).Padlock ... plasmid was dephos-phorylated by adding shrimp alcaline phosphatase (USB,Cleveland, OH, USA) (1 U for XmnI, 12 U for DraIII,2.5 U for XbaI) and incubating for 2 h at 37 °C. Phospha-tase was...