Structure of DNA

Boris Steipe Steipe at vms.biochem.mpg.de
Wed Dec 14 05:42:52 EST 1994


In article <3cfrn7$ik6 at panix.com>, jnr at panix.com (Josh Rubin) wrote:

> I would appreciate it if anyone would email me the basic physical
> dimensions of a DNA molecule, e.g., how many pairs of bases
> make one complete 360-degree turn, how far from one base pair to
> the next, and (if this makes sense) how far from the center 
> of the spiral are the base pairs. 

Stryer BIOCEMISTRY (every biochemists basic text) gives:
   10 base pairs per turn
   34 A per turn, i.e. 3.4 A per base (1 Angstrom = 10^^-10m)
   diameter is given as 20 A, distance from center depends on what you
mean:
      base ? phosphate ? closest some probe (e.g. a water molecule) can 
      approach ? hydrogen furthest away from center ? etc.
But: real DNA is somwhat bent and usually not exactly in the ideal B, A or
Z
     conformation.
If you need, I could mail you some real coordinates.

Greetings
Boris (steipe at vms.biochem.mpg.de)



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