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DNA

Exploring the Structure

We often think of DNA as a perfect, smooth double helix. In reality, DNA has a lot of local structure. The small piece of DNA shown here, from PDB entry 1bna, shows some of the common variations. At the top, the helix is bent to the left, distorted by the way that the helices are packed into the crystal. At the bottom, two of the bases are strongly propeller twisted--they are not in one perfect plane. This improves the way that the bases stack on top of one another along each strand, stabilizing the whole double helix. As more and more structures of DNA are studied, it is becoming clear that DNA is a dynamic molecule, quite flexible on its own, which is bent, kinked, knotted and unknotted, unwound and rewound by the proteins that interact with it.

This illustration was created with RasMol. You can create similar illustrations by clicking on the PDB accession code above and then picking one of the options under View Structure.

To locate DNA structures in the PDB using the SearchFields interface, in the "Contains Chain Type" section select DNA-YES and all others NO. A list of all DNA structures in the PDB as of November, 2001 is available here.

For information about DNA, click here.

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PDB Molecule of the Month November 2001, by David S. Goodsell

Last changed by: A.Honegger, 8/4/06