Until techniques in biochemistry and high-resolution crystallographic electron microscopy were developed during the 1970s which conclusively established the double helical shape and base-pairing rules for DNA, some scientists continued to question the validity of Watson's and Crick's model. One of them was Jerry Donohue, the American physical chemist who in 1953 had alerted Watson to errors in the configuration of the atoms of the bases of DNA as represented in most textbooks of biochemistry, enabling Watson to deduce the base pairing rule A=T and C=G. Donohue published an article in the September 12, 1969, issue of Science (vol. 165, p. 1091), in which he questioned whether Fourier syntheses, a method for calculating the distribution of electron density from amplitudes (seen in X-ray diffraction images) and assumed bond angles of molecules in crystals--and thus a method for inferring the structure of such molecules--did in fact provide evidence for the Watson-Crick structure, specifically the base pairs, as DNA researchers like Maurice Wilkins claimed. Donohue in his article presented electron density maps of combinations of various base pairs which he claimed fit Fourier analysis just as well as the canonical A=T and C=G pairs, thereby implying that other base pairs and thus other structures for DNA were conceivable, at least at the resolutions then attainable in X-ray diffraction images.
Crick, along with Wilkins and other DNA scientists, refuted Donohue's criticism and arguments in letters published in the March 27, 1970, issue of Science (vol. 167, p.1693). Donohue's letter was written in response to Crick's commentary, in which Crick challenged Donohue to build models of DNA based on his purported recalculation of the X-ray evidence.
Number of Image Pages:
2 (171,829 Bytes)
Date:
1970-05-06 (May 6, 1970)
Creator:
Donohue, Jerry
Recipient:
Crick, Francis
Source:
Original Repository: Wellcome Library for the History and Understanding of Medicine. Francis Harry Compton Crick Papers
Courtesy of the Wellcome Library for the History and Understanding of Medicine.
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Subject:
Medical Subject Headings (MeSH):
DNA
Crystallography, X-Ray
Exhibit Category:
Embryology and the Organization of DNA in Higher Organisms, 1966-1976
Relation:
Letter from Francis Crick to Jerry Donohue (May 20, 1970)
Letter from Francis Crick to Jerry Donohue (May 20, 1970)