Dorothy Crowfoot Hodgkin may be the most famous British scientist of whom most people have never heard. As such, she would be a very appropriate face for the new £50 note, on which the Bank of England wants to feature a picture of a scientist.
Hodgkin was the foremost leader and innovator in her field, and the major impact of her work led to her becoming the only female British scientist to win a Nobel Prize (so far). The 1964 award recognised her work in chemistry using a technique known as X-ray crystallography to find out the three-dimensional shapes of penicillin (1945) and vitamin B12 (1955).
Accurate knowledge of the shape of penicillin was absolutely pivotal in understanding how it could overcome bacterial infections. As as result, Hodgkin’s work is still extremely important in the development of new antibiotics, which are currently badly needed as some bacteria have developed resistance to existing drugs.
Hodgkin’s work also had an enormous impact on the treatment of diabetes. In 1969, after 35 years of enormously tenacious and brilliant work, she solved the 3D shape of the insulin molecule. Insulin is an important hormone used by the body to process sugars in food, and understanding its structure has helped untangle the mechanism of its action, with critical implications for human diabetes control.
Key to Hodgkin’s work was the technique of X-ray crystallography, a way of working out how a complex molecule is arranged in three dimensions. The way we find out this 3D shape is by growing tiny crystals (usually less than a tenth of a millimetre) of a substance so that its molecules are all lined up in an orderly array. We then hit this array with a very intense beam of X-rays and capture the resulting “diffraction pattern” of spots that indicate how the molecules interfere with the beam.
By capturing patterns from each side of the crystal and doing some fairly complicated mathematics, we can eventually get the average of the shapes of all the molecules, highlighting all the common features. This gives us a picture of the density of electrons in the molecule in 3D space, which we can use to show how the atoms of the molecule are arranged.Hodgkin’s model of penicillin. Wikipedia, CC BY-SA
In 1935, Hodgkin, along with her mentor J.D. Bernal, discovered that it was absolutely essential to keep the crystals wet with the liquid they are grown from (“mother liquor”) while X-raying them. If the liquid dries out, the molecules start to lose their ordered arrangement, and when hit with X-rays, they don’t give a clear pattern of spots.
Hodgkin’s pioneering work in crystallography gave birth to a whole new field that applied the methods she developed to large biologically important molecules, including DNA and proteins. We now know the 3D shapes of over 139,000 biological molecules, and all the information is stored in a completely open access database called the Protein Data Bank.
Inspirational role model
In this way, Hodgkin’s legacy is multifaceted. She was not only an exceptional scientist but also was, and continues to be, an inspirational role model to generations of researchers in the UK and elsewhere, both male and, very importantly, female.
I was thrilled to meet her in 1991 soon after I had changed research fields from nuclear physics to structural biology, and I had the opportunity to discuss the latest developments in crystallography with her. She inspired me to stay in the field and make my career in it, and I know many other scientists on whom she had a lasting positive influence.
She was also very active in standing up for her core beliefs as a pacifist. For 12 years she was president of Pugwash, an organisation founded in 1957 dedicated to reducing the danger of armed conflict and which sought peaceful solutions to global security threats. She even inspired her former student Margaret Thatcher, who reportedly kept a portrait of Hodgkin in 10 Downing Street, despite their differing politics.
Her life was a shining example to many so it would be entirely appropriate for us to honour her great scientific achievements, and help give her the public recognition she deserves, by putting her image on our new £50 notes.