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
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
If you need, I could mail you some real coordinates.
Boris (steipe at vms.biochem.mpg.de)