Maurice (Hugh Frederick) Wilkins - DNA

Biophysicist, born in Pongaroa, New Zealand. He studied at Birmingham and Cambridge universities, carried out wartime research into uranium isotope separation in California, then joined the Medical Research Council's Biophysics Research Unit at King's College, London in 1946, becoming deputy-director (1955) and director (1970–2). His X-ray diffraction studies of DNA helped Crick and Watson determine its structure, and he shared with them the Nobel Prize for Physiology or Medicine in 1962. His autobiography, The Third Man Of The Double Helix, was published in 2003.

Maurice Wilkins Discovery of the DNA Double Helix

Maurice Wilkins

Francis Crick

Rosalind Franklin

James Watson

Maurice Wilkins

Maurice Hugh Frederick Wilkins CBE FRS (15 December 1916 – 5 October 2004) was a New Zealand-born British physicist and Nobel Laureate who contributed research in the fields of phosphorescence, radar, isotope separation, and X-ray diffraction. He was most widely known for his work at King's College London on the structure of DNA, for which he, Francis Crick and James Watson were awarded the 1962 Nobel Prize for Physiology or Medicine for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material. His KCL colleague Rosalind Franklin made a major contribution to the discovery of the structure of DNA but she had died from cancer in 1958 and was therefore ineligible for the 1962 Nobel Prize award. Wilkins' work on DNA changed that. By 1951, Randall had established a major effort to solve the structure of collagen and Wilkins and Franklin represented a parallel effort to determine the structure of DNA.

DNA

DNA pioneers
William Astbury
Oswald Avery
Erwin Chargaff
Max Delbrück
Jerry Donohue
Raymond Gosling
Phoebus Levene
Linus Pauling
Sir John Randall
Erwin Schrödinger
Alec Stokes
Herbert Wilson

At King's College Wilkins pursued, among other things X-ray diffraction work on DNA that had been obtained from calf thymus by the Swiss scientist Rudolf Signer. The DNA from Signer's lab was much more intact than the DNA which had previously been isolated. Wilkins discovered that it was possible to produce thin threads from this concentrated DNA solution that contained highly ordered arrays of DNA suitable for the production of X-ray diffraction patterns. Using a carefully bundled group of these DNA threads and keeping them hydrated, Wilkins and a graduate student Raymond Gosling obtained X-ray photographs of DNA that showed that the long, thin DNA molecule in the sample from Signer had a regular, crystal-like structure in these threads. It was one of the X-ray diffraction photographs taken in 1950, shown at a meeting in Naples a year later, that sparked James Watson’s interest in DNA.

At that time Wilkins also introduced Francis Crick to the importance of DNA. Wilkins knew that proper experiments on the threads of purified DNA would require better X-ray equipment. Before the DNA sample from Signer was available, Gosling had been trying to make X-ray diffraction images of sperm. Late in 1950, Randall wrote to Franklin to inform her that rather than work on protein, she should take advantage of Wilkin's preliminary work and that she should do X-ray studies of DNA fibers made from Signer's DNA. No work had been done on DNA in the laboratory for several months; Franklin ended up with the DNA from Signer, Gosling became her PhD student and she had the expectation that DNA X-ray diffraction work was her project. Wilkins returned to the laboratory expecting that Franklin would be his collaborator and that they would work together on the DNA project that he had started. Franklin felt that DNA was now her project and would not collaborate with Wilkins, who then pursued parallel studies.

By November 1951 Wilkins thought he had evidence that DNA in cells as well as purified DNA had a helical structure. Alexander Stokes had solved the basic mathematics of helical diffraction theory and thought that Wilkin's X-ray diffraction data indicated a helical structure in DNA. This information from Wilkins along with additional information gained by Watson when he heard Franklin talk about her research during a King's College research meeting, stimulated Watson and Crick to create their first molecular model of DNA, a model with the phosphate backbones at the center.

By early 1953, it was clear that Franklin would simply drop her DNA work at the end of her fellowship that summer, or even sooner. Linus Pauling had published a proposed but incorrect structure of DNA, making the same basic error that had been made by Watson and Crick a year earlier. Some of those working on DNA in the United Kingdom, feared that Pauling would quickly solve the DNA structure once he recognized his error and put the backbones of the nucleotide chains on the outside of a model of DNA. After March 1952 Franklin concentrated on the X-ray data for the A-form of less hydrated DNA while Wilkins tried to work on the B-form. Wilkins was handicapped because Franklin had all of the good DNA. Wilkins got new DNA, but it was not as good as the original sample he had used in 1950 and which Franklin continued to use. About his only new results were for biological samples like sperm cells, which seemed to also suggest a helical structure for DNA. In the middle of 1952 Wilkins had for a time abandoned further DNA work when Franklin reported to him that her results made her doubt the helical nature of the A-form.

In early 1953 Watson visited King's College and Wilkins showed him a high quality image of the B-form X-ray diffraction pattern that had been produced by Franklin in March 1952. With the knowledge that Pauling was working on DNA and had submitted a model of DNA for publication, Watson and Francis Crick mounted one more concentrated effort to deduce the structure of DNA. Crick gained access to a progress reports from King's College that included useful information from Franklin about the features of DNA she had deduced from her X-ray diffraction data from Max Perutz, his thesis supervisor. Watson and Crick published their proposed DNA double helical structure in a paper in the journal Nature in April of 1953.

In recognition of the contribution from King's College, Watson and Crick agreed that Wilkins, Stokes and Wilson and Franklin and Gosling should each publish their x-ray diffraction work, which supported the proposed Crick-Watson model, in separate articles in the same issue of Nature.

Wilkins and others went on to repeat and extend much of Franklin's work, and produced much evidence to support the helical model of Crick and Watson. Maddox, Brenda, Rosalind Franklin: The Dark Lady of DNA, 2002. Rosalind Franklin and DNA. What Mad Pursuit: A Personal View of Scientific Discovery (Basic Books reprint edition) ISBN 0-465-09138-5 Watson, James D., The Double Helix: A Personal Account of the Discovery of the Structure of DNA, Atheneum, 1980, ISBN 0-689-70602-2 (first published in 1968) Krude, Torsten (Ed.) DNA Changing Science and Society: The Darwin Lectures for 2003 CUP 2003, includes a lecture by Sir Aaron Klug on Rosalind Franklin's involvement in the determination of the structure of DNA.