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Sven Furberg First Proposes a Helical Structure for DNA

1948 to 1952

In 1948 Sven Furberg, a Norwegian scientist working in London at Birkbeck College under J. D. Bernal, conducted researches leading to the first correct determination of the structure of a nucleotide, the main building block of DNA. Furberg was the first to propose a helical structure for DNA and the first to attempt building a model of DNA nucleotides. His original paper models of DNA were pasted into the back of his laboratory notebook, now preserved at the J. Craig Venter Institute.

Furberg's model was "an imaginative synthesis and constructive leap forward in the case of DNA by putting together a model that was single-stranded, eight-fold helix of nucleotides with stacked bases, 3.4Å apart as chemists knew aromatic rings should be, and with puckered five membered sugar rings displaying the conformation he had obtained from his own X-ray crystallographic analysis of cytidine, itself a virtuoso achievement in the late 1940s. Furberg's model was informally well publicized before its formal publication and surely was a striking advance despite being somewhat inaccurate, incomplete and devoid of insight as regards DNA function. The last flaw presumably was the reason that its other promising qualities were ignored even although they could have formed the basis of a further analysis by chemical crystallographers" (Arnott, Kibble & Shallice, "Maurice Hugh Frederick Wilkins," Biographical Memoirs of Fellows of the Royal Society [2006] 464-65).

In June 1949 Furberg distributed only about five or six copies of his typed PhD dissertation at Birkbeck College London, entitled An X-ray Study of Some Nucleosides and Nucleotides.

"Furberg, reasoning with marked brilliance and luck from data that were meager but included his own x-ray studies, got right the absolute three-dimensional configuration of the individual nucleotide: where Astbury had set sugar parallel to base, Furberg, in what he called the standard configuration, set them at right angles. As a structural element, that standard configuration was a powerful help. 'Furberg's nucleotide—correcting Astbury's error—was absolutely essential to us,' Crick told me. Furberg went on to draw a couple of models of DNA, one of which was a single chain in helical form with the bases sticking out flat and parallel to each other, rising 3.4 angstroms from one to the next, eight nucleotides making one complete turn of the screw in about 27 angstroms. Plausible physically, this helix had too little in it; it failed to account for the density of DNA. Furberg stopped building models and publishe his results in June of 1949—in his doctoral dissertation. . . .

"Over the next three years, Furberg's results appeared piecemeal in a series of papers. From his thesis, his models were well known to Randall's group at King's College. . . . Otherwise, Furberg's models remained almost unnoticed—even by Bernal, who wrote, in 1968, that they had contained 'the key to the whole double helix story' and blamed himself for 'letting the opportunity slip'; Furberg at last got his helical model into print in Acta Chemica Scandinavica late in 1952, in time for Watson and Crick to cite it in the notes to their announcement of the successful solution the next spring" (Judson, The Eighth Day of Creation, 94).

Furberg, "On the Structure of Nucleic Acids," Acta Chemica Scandinavica (1952) 634-40.

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