Intercalating fluorescence dye YOYO-1 prevents the folding transition in giant duplex DNA

義永 那津人


Recently, it has become clear that, with the addition of polyamines, giant DNA molecules of size greater than 10 kbp exhibit all-or-none switching between elongated coil and folded compact states. Here, the effects of the intercalating fluorescent labeling dye, YOYO-1, and the minor-groove binding fluorescent labeling dye, DAPI, on the folding transition of single giant T4 DNA (166 kbp) induced by spermidine 3+ were examined, by use of the experimental technique of single molecular chain observation with fluorescence microscopy. It is found that the intercalating dye, YOYO-1, markedly prevents the folding transition, whereas the minor-groove binding dye, DAPI, exhibits negligible effect on the folding transition. This action of YOYO-1 is discussed in relation to the biological effect of intercalators.


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