Sunday, October 18, 2015

Dorothy Crowfoot Hodgkin (May 12, 1910 – July 29, 1994)

Dorothy Mary Crowfoot was born on 12 May 1910 in Cairo, Egypt, to John Winter Crowfoot, an archaeologist and classical scholar, and Grace Mary Crowfoot née Hood, an archaeologist and expert on Ancient Egyptian textiles. She lived in the English expatriate community in Egypt, returning to England only a few months each year. During one of those stays in England, when Hodgkin was four, World War I began. Her mother lost four brothers in the war. Separated from her parents, who would return to Egypt, she was left under the care of relatives and friends until after the end of the war when her mother came to England for one year, a period that she later described as the happiest in her life.

In 1921, she entered the Sir John Leman Grammar School in Beccles. Only once, when she was thirteen, did she make an extended visit to her parents, who by then had moved to Khartoum, although both parents continued to visit England each summer.

She developed a passion for chemistry from a young age, and her mother fostered her interest in science in general. Her state school education left her without Latin or a further science subject, but she took private tuition in order to enter the University of Oxford entrance examination. At the age of 18 she started studying chemistry at the University of Oxford (Somerville College, Oxford).

She studied for a Doctor of Philosophy at the University of Cambridge under the supervision of John Desmond Bernal, where she became aware of the potential of X-ray crystallography to determine the structure of proteins, working with him on the technique's first application to the analysis of a biological substance, pepsin.

In 1933 she was awarded a research fellowship by Somerville College, and in 1934, she moved back to Oxford. The college appointed her its first fellow and tutor in chemistry in 1936, a post which she held until 1977. In the 1940s, one of her students was Margaret Roberts, the future Prime Minister Margaret Thatcher, who installed a portrait of Hodgkin in Downing Street in the 1980s.

Together with Sydney Brenner, Jack Dunitz, Leslie Orgel, and Beryl M. Oughton, she was one of the first people in April 1953 to travel from Oxford to Cambridge to see the model of the double helix structure of DNA, constructed by Francis Crick and James Watson, based on data acquired by Rosalind Franklin. According to the late Dr. Beryl Oughton, later Rimmer, they all traveled together in two cars once Dorothy Hodgkin announced to them that they were off to Cambridge to see the model of the structure of DNA.

In 1960, she was appointed the Royal Society's Wolfson Research Professor, a position she held until 1970. This provided her salary, research expenses and research assistance to continue her work at the University of Oxford.

Hodgkin was particularly noted for discovering three-dimensional biomolecular structures. In 1945, working with C. H. (Harry) Carlisle, she published the first such structure of a steroid, cholesteryl iodide (having worked with cholesteryls since the days of her doctoral studies). In 1945, she and her colleagues solved the structure of penicillin, demonstrating (contrary to scientific opinion at the time) that it contains a β-lactam ring. However, the work was not published until 1949.

In 1948, Hodgkin first encountered vitamin B12, and created new crystals. From these, she deduced the presence of a ring structure because the crystals were pleochroic, a finding which she later confirmed using X-ray crystallography. Scientists from Merck had previously crystallized B12, but had published only refractive indices of the substance. The final structure of B12, for which Hodgkin was later awarded the Nobel Prize, was published in 1955.

Insulin was one of her most extraordinary research projects. It began in 1934 when she was offered a small sample of crystalline insulin by Robert Robinson. The hormone captured her imagination because of the intricate and wide-ranging effect it has in the body. However, at this stage X-ray crystallography had not been developed far enough to cope with the complexity of the insulin molecule. She and others spent many years improving the technique. Larger and more complex molecules were being tackled until in 1969 – 35 years later – the structure of insulin was finally resolved. But her quest was not finished then. She cooperated with other laboratories active in insulin research, gave advice, and traveled the world giving talks about insulin and its importance for diabetes.

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