Photo 51 Discovery of the DNA Double Helix

Photo 51, an X-ray diffraction image of sodium salt of DNA. B configuration

Francis Crick

Rosalind Franklin

James Watson

Maurice Wilkins

Cavendish Laboratory

King's College London

Photo 51

Photo 51 is the nickname given to an X-ray diffraction image of DNA taken by Rosalind Franklin in 1952^[1] that was critical evidence^[2] in identifying the structure of DNA.^[3] The photo was taken by Franklin while working at King's College London in Sir John Randall's group.

James D. Watson was shown the photo by Maurice Wilkins, who had been given it by Raymond Gosling, whether this was or was not with Franklin's approval is a matter of opinion. Along with Francis Crick, the three men used it to jointly win the 1962 Nobel Prize in Physiology or Medicine. As the Nobel prize is not awarded posthumously, Franklin, whose breakthrough data was used to formulate the DNA structure, had died in 1958, thus was not eligible for nomination. It was the critical evidence^[4] that led to the confirmation of the postulated double helical structure of DNA, published during 1953 in a series of five articles in the journal Nature.^[5] Franklin and Raymond Gosling's own publication in the same issue of Nature was the first publication of this more clarified X-ray image of DNA.^[6]

The image was referred to in a letter from Max Perutz to Harold Himsworth of the Medical Research Council dated 6th April 1953:

"The structure was built by Watson and Crick on the basis of stereographic and genetic arguments. They also used the published X-ray data of Astbury and of the MRC unit at King’s College London, plus a certain amount of unpublished X-ray data which they had seen or heard about at King’s. All these X-ray data were either poor, or referred to a different form of structure, and while they indicated certain general features of the structure of DNA they did not give a guide to its detailed character.

While Watson and Crick were building their structure here, Miss Franklin and Gosling at King’s obtained a new and very detailed picture of DNA. Watson and Crick only heard of this photograph when they sent the first draft of their paper to King’s, but it now appears than this new photograph confirms the important features of their structure." ^[7]

Subsequently Perutz also referred to the same image in a letter to "The Times" dated 19th October 1962 in the context of the award of the 1962 Nobel Prize for Physiology or Medicine:

"In 1953 Watson, then a visiting Research Fellow at the Cavendish Laboratory, and Crick, a member of the Medical Research Council’s molecular biology unit there, built an atomic model of deoxyribo-nucleic acid. Their model had been inspired,and was later proved, by the remarkable X-ray diffraction pictures taken by Wilkins and his collaborators at the Medical Research Council’s biophysics unit at King’s College London." ^[8]

[edit] References

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