Crowfoot, Dorothy

Hodgkin, Crowfoot Dorothy (p. 132, Plate 21) born in 1910 in Cairo, she studied chemistry at Oxford from 1928-32 and concentrated on X-ray crystallography with J.D. Bemal at Cambridge in 1934 she returned to Oxford where she has remained, except for brief intervals, ever since. She became University lecturer and demonstrator in 1946, University Reader in X-ray crystallography in 1956 and Wolfson Research Professor of the Royal Society in 1960-1983. Apart from X-ray studies of insulin (p. 159) she also did research on penicillin (in 1942) and on vitamin Bj2 (in 1948). She received the Nobel Prize in chemistry 1964. In 1937 she married Thomas Hodgkin, historian of Africa and the Arab world. 

Cobalt is one of twenty-seven known elements essential to humans (28) (see Mineral NUTRIENTS). It is an integral part of the cyanocobalamin [68-19-9] molecule, ie, vitamin B 2> only documented biochemically active cobalt component in humans (29,30) (see Vitamins, VITAMIN Vitamin B 2 is not synthesized by animals or higher plants, rather the primary source is bacterial flora in the digestive system of sheep and cattle (8). Except for humans, nonmminants do not appear to requite cobalt. Humans have between 2 and 5 mg of vitamin B22, and deficiency results in the development of pernicious anemia. The wasting disease in sheep and cattle is known as bush sickness in New Zealand, salt sickness in Florida, pine sickness in Scotland, and coast disease in AustraUa. These are essentially the same symptomatically, and are caused by cobalt deficiency. Symptoms include initial lack of appetite followed by scaliness of skin, lack of coordination, loss of flesh, pale mucous membranes, and retarded growth. The total laboratory synthesis of vitamin B 2 was completed in 65—70 steps over a period of eleven years (31). The complex stmcture was reported by Dorothy Crowfoot-Hodgkin in 1961 (32) for which she was awarded a Nobel prize in 1964. 

In spite of the slow development of crystal structure analysis, once it did take olT it involved a huge number of investigators tens of thousands of crystal structures were determined, and as experimental and interpretational techniques became more sophisticated, the technique was extended to extremely complex biological molecules. The most notable early achievement was the structure analysis, in 1949, of crystalline penicillin by Dorothy Crowfoot-Hodgkin and Charles Bunn this analysis achieved something that traditional chemical examination had not been able to do. By this time, the crystal structure, and crystal chemistry, of a huge variety of inorganic compounds had been established, and that was most certainly a prerequisite for the creation of modern materials science. 

In the 6jS-bromoacetyI derivative of 3,5a-cyclo-cholestan-6jS-oI, the 6 -oxygen-l9 carbon distance in the crystal is about 3.19 A (private communication from Prof. Dorothy Hodgkin, Oxford), (f. also H. R. Harrison, D. Crowfoot Hodgkin, E. N. Maslen and W. D. S. Motherwell./. Chem. Soc. C, 1971, 1275). 

Dorothy Crowfoot Hodgkin (Oxford) determinations by X-ray techniques of the structures of important biochemical substances. 

Hodgkin, Dorothy Crowfoot, 248 Homarus Americanus, 157 Homogeneous Uniform in composition, 2,4-5... 

Kathleen Lonsdale, an x-ray crystallographer, was the first woman elected to the Royal Society of London Dorothy Crowfoot Hodgkin was the first woman chemist elected. 

Chemists commonly use a process called X-ray diffraction to determine the structure of a compound. Two pioneers of X-ray diffraction were Rosalind Franklin and Dorothy Crowfoot Hodgkin. Franklin s work on the DNA molecule was instrumental in the discovery of its helical shape. Nobel Prize winner Hodgkin discovered the structure of complex molecules, such as cholesterol, penicillin, insulin, and vitamin B-12. Find out about X-ray diffraction how it works and the types of scientists who employ this technology. 

The isolation of the pure material was not the end of the story. Deducing the structure of vitamin B12 was a saga itself. Dorothy Crowfoot Hodgkin, an English scientist, won a Nobel Prize in Chemistry in 1964 in part for getting this structure. This was one of the early triumphs of the technique of X-ray diffraction. She was a amazingly productive structural chemist, getting the structures for cholesterol and insulin as weU. 

Dorothy Crowfoot Great Britain x-ray techniques of the structmes of biochem-... 

From 1940 to 1945, researchers sought the structure of penicillin. Several forms of penicillin were discovered. In 1945, Dorothy Mary Crowfoot Hodgkin (1910—1994) used x-ray crystallography to determine the structure of penicillin. John C. Sheehan (1915—1992) synthesized a penicillin called penicillin V in 1957 at Massachusetts Institute of Technology. Although Sheehans work showed that penicillin could be synthesized, the method was not practical on a commercial level. Currently, about 45,000 tons of penicillins are produced annually worldwide. 

The three-dimensional structure of the cofactor was determined by Dorothy Crowfoot Hodgkin in 1956, using x-ray crystallography. 

Dorothy M. Crowfoot Hodgkin Chemistry X-ray structures, vitamin B12... 

Creutzfeldt-Jakob disease 248 Crick, Francis H. C. 84, 200 Cristae of mitochondria 14 Crossing-over 18 Crosslinking 79 Crotonase. See Enoyl hydratase Crowfoot Hodgkin, Dorothy M. 84 Cruciform structure in nucleic acids 229 Crustacea 24 Cruzain 619 Cryoenzymology 469 elastase 616 Cryoprotectants 191 Crystallins 169 Crystallography 131-137 electron 131 X-ray 132-137 Crystals, liquid 392-394 Crystal systems 133 Cubic symmetry... 

Early protein crystallographers, proceeding by analogy with studies of other crystalline substances, examined dried protein crystals and obtained no diffraction patterns. Thus X-ray diffraction did not appear to be a promising tool for analyzing proteins. In 1934, J. D. Bernal and Dorothy Crowfoot (later Hodgkin) measured diffraction from pepsin crystals still in the mother liquor. Bernal and Crowfoot recorded sharp diffraction patterns, with reflections out to distances in reciprocal space that correspond in real space to the distances between atoms. The announcement of their success was, in effect, a birth announcement for protein crystallography. 

Dorothy Crowfoot Hodgkin X-ray crystal structure of vitamin B12... 

Farago, Peter (1977). Interview with Dorothy Crowfoot Hodgkin. Journal of Chemical Education 54(4) 214—216. 

Miriam Rossi, Dorothy Crowfoot Hodgkin (1910-1994), Crystallographer, in Shearer and Shearer, pp. 181-186 and Georgina Ferry, Dorothy Hodgkin A Life (New York Granta Books, 1998). On Lise Meitner, a famous near-Nobelist, see Clara C. Callahan, Lise Meitner (1878-1968), Physicist, in Shearer and Shearer, pp. 263-268 and Ruth Sime, Lise Meitner, A Life in Physics (Berkeley University of California Press, 1996). 

In retrospect, it is quite remarkable that at the same time when Chatt s group performed their studies on organometallic compounds with phosphine ligands, Dorothy Crowfoot-Hodgkin completed her work on the structure of vitamine B12, for which she was awarded the Nobel Prize for Chemistry in 1964. As far as we presently know, vitamine BJ2 is the only natural product containing a transition metal-carbon cr-bond [see P. G. Lenhert, and D. Crowfoot-Hodgkin, Structure of the 5,6-Dimethylbenzimidazolylcobamide Coenzyme, Nature 192,937-938 (1961)]. 

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