World of Scientific Discovery on Dorothy Crowfoot Hodgkin
Wilhelm Roentgen's discovery of the X-ray resulted in the creation of several offshoot disciplines. One of these is X-ray crystallography, first practiced by William Henry Bragg (1862-1942) and his son, for which they were awarded the 1952 Nobel Prize for physics. This new scientific tool was utilized by many researchers, but none matched the insightful approach nor the success rate of Dorothy Crowfoot Hodgkin.
Dorothy Crowfoot was born in Cairo, Egypt, in 1910. The daughter of an English archaeologist, she became quickly accustomed to travel, and at an early age had visited archeological sites all over the world. She eventually went to Great Britain to attend Somerville College at Oxford. There she studied the structure of crystals, a subject that had fascinated her since high school (in fact, she began conducting mineral experiments at age ten). Graduating in 1932, she received a small research grant that enabled her to enroll in graduate courses at Cambridge. Under the tutelage of Irish physicist J. D. Bernal (1901-1971), Crowfoot studied X-ray examinations of different crystals. She continued this line of study when she returned to Somerville, this time as a lecturer, and received her doctorate at Cambridge University in 1937. That same year she married Thomas Hodgkin, a historian at Oxford.
The first great task for X-ray crystallographers came in 1941. That year, Time magazine declared penicillin the new wonder drug. Actually discovered in 1929 by Sir Alexander Fleming, penicillin was for years used sparingly and at few hospitals, largely due to the difficulty of its extraction and purification. As World War II escalated, however, the need for antibiotics grew explosively. The only solution was to develop a process by which penicillin could be synthesized, rather than extracted from scarce natural sources. In order to accurately synthesize a substance, its atomic and molecular structure must be known in great detail, knowledge that could be gained only through X-ray crystallography. For this purpose, Dorothy Hodgkin was asked to study the structure of penicillin crystals.
Consisting of seventeen atoms, the penicillin molecule was the most complex yet examined using X-rays. To assist with the exhaustive plotting of molecular points, Hodgkin used a very primitive punch-card style computer--the first direct application of an electronic computer in biochemical research. Still, it took Hodgkin's research group nearly five years to map the atomic structure of a penicillin crystal, after which the antibiotic could finally be mass-produced.
Immediately after solving the penicillin problem, Hodgkin's team applied their groundbreaking techniques to the X-ray analysis of 12 vitamin B12, used by doctors in the prevention of pernicious anemia. The B12 molecule contained more than ninety atoms and was therefore significantly more challenging than penicillin had been. In order to simulate the process of X-ray crystallography on a large scale, Hodgkin constructed a model of the vitamin B12 molecule out of heavy wire. By shining a light through the model and observing the shadows created, she could anticipate the light and dark areas within the molecule. Though it took several years to determine the structure of vitamin B12, this was still far less time than would have been required using chemical means.
The techniques and tools used by Hodgkin and her research group were soon recognized as the simplest and most accurate means by which the molecular structures of crystals could be ascertained. Hodgkin herself was awarded the 1964 Nobel Prize for chemistry. She continued to research using X-ray crystallography for several years and in 1969 succeeded in completing the structure of insulin, used to treat diabetes. Consisting of 777 atoms, the complete structure of insulin crystals had thwarted many scientific teams before Hodgkin's group applied very specialized computers to the task.
This is the complete article, containing 605 words
(approx. 2 pages at 300 words per page).
