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Tuesday, January 02, 2007

A Reason for (some guarded) Optimism

is the freely available information (such as below) archived randomly on the internet. As long as the power stays on, we may be okay.

The paper which first suggested the double helix structure for DNA [asterisk and links mine]:

A Structure for Deoxyribose Nucleic Acid
J. D. Watson and F. H. C. Crick (1)

April 25, 1953 (2),
Nature (3), 171, 737-738

We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable* biological interest.

A structure for nucleic acid has already been proposed by Pauling (4) and Corey1. They kindly made their manuscript available to us in advance of publication. Their model consists of three intertwined chains, with the phosphates near the fibre axis, and the bases on the outside. In our opinion, this structure is unsatisfactory for two reasons:

(1) We believe that the material which gives the X-ray diagrams is the salt, not the free acid. Without the acidic hydrogen atoms it is not clear what forces would hold the structure together, especially as the negatively charged phosphates near the axis will repel each other.

(2) Some of the van der Waals distances [more van der Waals] appear to be too small.
The whole paper is worth reading. It's fairly short.

*That's some fine and beautiful understatement.

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