MOLECULAR STICK-SLIP MOTION REVEALED BY OPENING DNA WITH PICONEWTON FORCES

We have pulled apart the two strands of a DNA double helix. The forces measured during this process show a sequence specific variation on th e piconewton scale. Opening two helical molecules with the same sequen ce from opposite sides gives two signatures which are not simply relat ed by symmetry. In a theoretical model, this is explained as a molecul ar stick-slip motion which does not involve instabilities and is deter mined by the sequence.