B. Essevazroulet et al., MECHANICAL SEPARATION OF THE COMPLEMENTARY STRANDS OF DNA, Proceedings of the National Academy of Sciences of the United Statesof America, 94(22), 1997, pp. 11935-11940
We describe the mechanical separation of the two complementary strands
of a single molecule of bacteriophage lambda DNA. The 3' and 5' extre
mities on one end of the molecule are pulled progressively apart, and
this leads to the opening of the double helix. The typical forces alon
g the opening are in the range of 10-15 pN. The separation force signa
l is shown to be related to the local GC vs. AT content along the mole
cule. Variations of this content on a typical scale of 100-500 bases a
re presently detected.