"A Structure for DNA"

Date:
[1953]
Reference:
PP/CRI/H/1/11/2
Catalogue details

Licence: In copyright

Credit: "A Structure for DNA". Source: Wellcome Collection.

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    Pauling and Corey'* have recently proposed a structure for nucleic acid. They were kind enough to make t eir manuscript available to us in advance of publication. In our opinion their 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 Weals distances appear to be too small. We wish to put forward a radically different structure for the salt of desoxyribose nucleic acid (D.H.A.). This structure has two helical chains each coiled round the same axis. The two chains (but not their bases ; are related by a dyad perpendicular to this axis. Both chains follow right-handed helices, bat owing to the dyad the sequences of the atoms in the two chainsímn in opposite directions. 2 Each chain loosely resembles Furberg*s ' model No.l; that is, the bases are on the inside of the helix and the phosphates on the outside. The configuration of the sugar and the atoms near it is close to Furberg*s standard configuration, the sugar being roughly perpendic ular to the attached base. There is a residue on each chain every 3.4 $ in the z direction. We have assumed an angle of 36° between adjacent residues in the same chain, so that the structure repeats after 10 residues on each chain, that is, after 3k I. The distance of a