DNA: Difference between revisions

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, <scene name='DNA/1bna/6'>1bna</scene>, 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.