A comparative representation of the three forms of DNA
Sources [1]
To re-align the three molecules, reload this page.
Change rendering:
Helical Parameters of the three forms of DNA
DNA is a very flexible molecule and has the ability to exist in various forms based on the environmental conditions. Naturally occurring DNA double helices are classified into A, B and Z-types. A and B-forms of DNA are the right handed forms whereas Read more about morphing is the left handed form. When hydrated the DNA generally assumes B-form. The A conformation is found when there is little water to interact with the helix and is also the conformation adopted by the RNA. The formation of Z-DNA occurs with the methylation of deoxycytosine residues and also during transcription where negative supercoiling stabilizes it.
| Parameter
|
A-DNA
|
B-DNA
|
Z-DNA
|
| Helix sense |
right-handed |
right-handed |
left-handed
|
| Residues per turn |
11 |
10.5 |
12
|
| Axial rise [Å] |
2.55 |
3.4 |
3.7
|
| Helix pitch(°) |
28 |
34 |
45
|
| Base pair tilt(°) |
20 |
−6 |
7
|
| Rotation per residue (°) |
33 |
36 |
-30
|
| Diameter of helix [Å] |
23 |
20 |
18
|
| Glycosidic bond configuration<br\>dA,dT,dC<br\>dG |
<br\>anti<br\>anti |
<br\>anti<br\>anti |
<br\>anti<br\>syn
|
| Sugar pucker<br\>dA,dT,dC<br\>dG |
<br\>C3'-endo<br\>C3'-endo |
<br\> C2'-endo<br\>C2'-endo |
<br\>C2'-endo<br\>C3'-endo
|
| Intrastrand phosphate-phosphate distance [Å] <br\>dA,dT,dC<br\>dG |
<br\>5.9<br\>5.9 |
<br\>7.0<br\>7.0 |
<br\>7.0<br\> 5.9
|
| Sources: [2][3][4]
|
Structural Transformation between A and B DNA
This animated model displays the structural transformation between A and B forms of DNA.
Rendering: Reset the model
Control of animation:
Other interesting views:
Source of morphs: [1]
Read more about morphing
- ↑ Krebs WG, Gerstein M. The morph server: a standardized system for analyzing and visualizing macromolecular motions in a database framework. Nucleic Acids Res. 2000 Apr 15;28(8):1665-75. PMID:10734184
| |
See also
References
- ↑ Nucleic Acid Canonical Coordinates https://nucleix.mbu.iisc.ac.in/nacc/index.html
- ↑ Rich A, Nordheim A, Wang AH. The chemistry and biology of left-handed Z-DNA. Annu Rev Biochem. 1984;53:791-846. PMID:6383204 doi:https://dx.doi.org/10.1146/annurev.bi.53.070184.004043
- ↑ Wang AH, Quigley GJ, Kolpak FJ, Crawford JL, van Boom JH, van der Marel G, Rich A. Molecular structure of a left-handed double helical DNA fragment at atomic resolution. Nature. 1979 Dec 13;282(5740):680-6. PMID:514347
- ↑ Sinden, Richard R (1994-01-15). DNA structure and function (1st ed.). Academic Press. pp. 398. ISBN 0-12-645750-6.
proteopedia link
