Celebrating women in science on International Women’s Day: Dorothy Mary Hodgkin
Dorothy Mary Hodgkin OM FRS (12 May 1910 – 29 July 1994), known professionally as Dorothy Crowfoot Hodgkin or simply Dorothy Hodgkin, was a British biochemist who developed protein crystallography, for which she won the Nobel Prize in Chemistry in 1964.
She advanced the technique of X-ray crystallography, a method used to determine the three-dimensional structures of biomolecules. Among her most influential discoveries are the confirmation of the structure of penicillin that Ernst Boris Chain and Edward Abraham had previously surmised, demonstrating (contrary to scientific opinion at the time) that it contains a β-lactam ring. She also confirmed the structure of vitamin B12, for which she became the third woman to win the Nobel Prize in Chemistry. 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 1948, Hodgkin first encountered vitamin B12 and created new crystals. Vitamin B12 had first been discovered by Merck earlier that year. Vitamin B12 had a structure at the time that was almost completely unknown, and when Hodgkin discovered it contained cobalt, she realized the structure actualization may be determined by x-ray crystallography analysis. The large size of the molecule, and that the atoms were largely unaccounted for – aside from cobalt – posed a challenge in structure analysis that hadn’t been previously explored.
|Molecular structure of vitamin B12, by NEUROtiker (Own work) [Public domain], via Wikimedia Commons|
From these crystals, she deduced the presence of a ring structure because the crystals were pleochroic, a finding which she later confirmed using X-ray crystallography. The B12 study published by Hodgkin was described by Lawrence Bragg as being as significant “as breaking the sound barrier.” Scientists from Merck had previously crystallised 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.
In 1969, after 35 years of work and five years after winning the Nobel Prize, Hodgkin was able to decipher the structure of insulin. X-ray crystallography became a widely used tool and was critical in later determining the structures of many biological molecules where knowledge of structure is critical to an understanding of function. She is regarded as one of the pioneer scientists in the field of X-ray crystallography studies of biomolecules.
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