Z-DNA model tour

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 30: Line 30:
Now change the display to make it show the <scene name='72/725870/Space_filling_bbone/1'>sugar-phosphate backbone as pseudo-bonds</scene> connecting the phosphate atoms. Now the bases are easier to see. Now the bases are easier to see. Notice how they are stacked upon each other and are nearly perpendicular to the axis of the double helix. But notice that the base pairs do not stack upon each other equivalently. The backbone also is not a continuous curve, it "zig-zags" back and forth (hence "Z"-DNA).
Now change the display to make it show the <scene name='72/725870/Space_filling_bbone/1'>sugar-phosphate backbone as pseudo-bonds</scene> connecting the phosphate atoms. Now the bases are easier to see. Now the bases are easier to see. Notice how they are stacked upon each other and are nearly perpendicular to the axis of the double helix. But notice that the base pairs do not stack upon each other equivalently. The backbone also is not a continuous curve, it "zig-zags" back and forth (hence "Z"-DNA).
-
You can <scene name='72/725442/Zoom_pairs/1'>look at just four of the base pairs.</scene>.You are looking into the major groove and the colors of the base pairs alternate. You can also <scene name='72/725442/Zoom_pairs_only/1'>looks at just the bases</scene>.
+
<scene name='72/725870/Zoom_pair/1'>In this view</scene>, the molecule is shown in stick representation, with the backbone in yellow and sets of base pairs in red and blue. Notice how the blue bases stack well on the adjacent blue ones, but not on adjacent red ones, and vice versa. So it is the dinucleotide unit, rather than mononucleotide that is the repeating unit of the structure. This explains the need for alternating purines and pyrimidines to form Z-DNA.
-
Each base pair stacks on the next similarly, as shown from <scene name='72/725442/Zoom_pairs_top/1'>this top view</scene>. This is the <scene name='72/725442/Zoom_pairs_only_top/1'>same top view of just the bases</scene>. A-form DNA also stacks in this way, but compare this with Z-DNA, which behaves much differently.
+
-
DNA is usually found in the B form under physiological conditions. The B-form conformation is stabilized by water molecules bound to the minor groove. You can see them as red dots <scene name='72/725442/Water_spine/1'>in this view</scene>. Sometimes kinks are found in the B helix at transcriptional control regions. These kinks can either be intrinsic to the DNA sequence or caused by transcription factor binding.
+
You can see <scene name='72/725870/Zoom_pairs_only/1'>the same view without the backbone</scene> here.Going 5' to 3', there is good stacking within the GpC dinucleotide, but not between them (CpG).
-
 
+
A also illustrates the stacking arrangement.
-
You can compare it with the DNA forms by looking at this [http://proteopedia.org/wiki/images/d/d3/JnABZ3d.gif 3D red-blue stern picture of A, B, and Z DNA]
+
. You can also see this
 +
You can compare it with the DNA forms by looking at this [http://proteopedia.org/wiki/images/d/d3/JnABZ3d.gif 3D red-blue stereo picture of A, B, and Z DNA]
</StructureSection>
</StructureSection>
== References ==
== References ==

Revision as of 20:46, 21 February 2016

Z-form DNA model

B-DNA

Drag the structure with the mouse to rotate

References

R. E. Dickerson, H. R. Drew, B. N. Conner, R. M. Wing, A. V. Fratini & M. L. Kopka (1982) The anatomy of A-, B-, and Z-DNA. Science 216: 475-485 [1] JSmol in Proteopedia [2] or to the article describing Jmol [3] to the rescue.

Proteopedia Page Contributors and Editors (what is this?)

James Nolan, Michal Harel

Retrieved from "http://52.214.119.220/wiki/index.php/Z-DNA_model_tour"
Personal tools