Images of the DNA double helix in water

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Science  02 Jun 1989:
Vol. 244, Issue 4908, pp. 1063-1064
DOI: 10.1126/science.2727694


The scanning tunneling microscope can image uncoated DNA submerged in water. The grooves of the double helix were clearly resolved in images of the 146-base pair fragment extracted from calf thymus nucleosome. In contrast to images obtained with dry DNA, the helix pitch varied only a small amount (36 +/- 5 angstroms). The path of the helix shows considerable variation. It is quite straight when the molecules are densely packed, but it curves and bends in isolated molecules.

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