"The molecular structure of the gene"

Date:
[1953]
Reference:
PP/CRI/H/1/12/3
Catalogue details

Licence: In copyright

Credit: "The molecular structure of the gene". Source: Wellcome Collection.

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    THE MOLECULAR S TRUC TT 'RE OP THE GBmB We haVe recently put forward a structure* for the salt of 2,3 deoxyribonucleic acid (D.N. A. ). X-ray evidence obtained by the workers at King*s College, London, and presented at the same time, gives qualitative support to our structure, and is incompatable with all other structures so far proposed. It should he noted that most of this X-ray evidence can be considered as independent confirmation,as only a small part of the X-ray data was used by us to derive the structure. Our model is also supported by the analytical datk'^, which again we did not use in deriving the structure. The main X-ray evidence has come from fibres of sodium 2 thymonucleare. However, it has been shown by Wilkins , and his co-workers that similar X-ray spacings are given by intact biological materials, so that it is unlikely that the structure is an artefact. The proposed structure will not be completely proved until a more extensive comparison has been made with the X-ray data. However, we now feel sufficient confidence in its general correctness for us to consider its genetical implications. The structure has two novel features. Th^yare: (1) it contains two polynucleotide chains, each of which follows a helical path round a common axis. (2) the two chains are held together by specific pairs of bases. In detail, each pair of bases consists of a base from one chain hydrogen-bonded to a baBe from the other chain. One of the pair must be a purine and the other a pyrimidine for hydrogen-bonding to occur. If we assume that the bases only occur in the most plausible tautomeric forms, then the nature of the proposed structure is such that only specific pairs of bases can be formed. These pairs are;