In 1932 Dorothy Crowfoot graduated from Somerville College at
Oxford with a degree in chemistry (her interest in chemistry and
crystals began when she was young and was encouraged by her parents
and their associates to develop this interest). While studying
in the department of mineralogy and crystallography, she employed
the physical science of X-ray crystallography (first developed
by W. L. Bragg) to aid her in determining the structural arrangement
of the atoms in simple salts and minerals such as thallium dialkyl
halides. This was the first of what would be many X-ray studies.
Dr. Hodgkin discovered that crystals are a solid composed of
atoms arranged in a regular and repeated pattern. She later took
this method one step further and used it to analyze more complex
In 1933 Dr. Hodgkin began working with J. D. Bernal on her doctorate
degree. Bernal strengthened her lifelong interest in structural
biology. She felt that the scientific world had ceased to know
any boundaries while conducting her research with him. Dr. Hodgkin
stated in a published paper regarding her work with Bernal, "
explored the crystallography of a wide variety of natural products,
the structure of liquids and particularly water, Rochelle salt,
isomorphous replacement and phase determination, metal and pepsin
crystals, and speculated about muscular contraction."
Crystallography was a relatively new science when Dr. Hodgkin
began her research. It was a combination of mathematics, physics,
and chemistry. Max von Laue, William Henry Bragg, and William
Lawrence Bragg were its early pioneers. They determined that
atoms in a crystal deflected X-rays and that these deflected X-rays
interfered or interacted with each other. A bright spot could
be captured on photographic film if they interacted with each
other. This brightness was canceled if they interfered with each
other. These X-ray spots, or diffraction patterns, reveal a mathematical
relationship to the positions of individual atoms within the crystal.
By shining the X-ray through the crystal, capturing the pattern
on film, and completing the mathematical calculations on the distances
and relative positions of the spots, they were able to determine
the molecular structure of almost any crystalline material. Through
her research, Dr. Hodgkin was able to determine the structural
layout of atoms and the overall molecular shape of numerous molecules.
This is the information which contributes to molecular biological
It was during this time that Dr. Hodgkin, along with Bernal, recorded
the first X-ray diffraction pattern of a globular protein. These
photographs were obtained from crystals of pepsin grown by John
Philpot in Uppsala. These protein crystals were extremely difficult
and tedious to work with in the early 1930s because of the lack
of technology. Proteins are polymers, long chains of repeating
units, that are larger and more complicated than other biological
molecules. They perform their biological functions by folding
over on themselves and assuming specific three-dimensional shapes.
Through this research, Bernal and Hodgkin were able to determine
that "the arrangement of atoms inside the protein molecule
is of a perfectly definite kind." They also determined that
protein crystals should be studied with their mother liquid surrounding
them and not air-dried as was the standard of the time. This
marked the start of macromolecular crystallography which still
dominates current structural biology. This also led to subsequent
research on the structures of insulin, hemoglobin, and viruses.
Also at this time, she began her research of sterols which she
continued after her return to Oxford. She completed detailed
X-ray analysis of cholesterol iodide's molecular structure and
over 100 steroids. She reported their unit-cell dimensions, reactive
indices with respect to their crystallographic axes, showed the
molecules crystal packing, and their hydrogen-bond scheme. This
was a breakthrough in crystallography because it was the first
analyses based on three-dimensional calculations and it established
the stereochemistry at each carbon atom of the steroids.
In 1934, upon her return to Oxford University she crystallized
and X-ray photographed insulin. This was only the second protein
to be studied and was a major achievement for Dr. Hodgkin because
she completed the crystallization and photographs on her own.
This analysis was completed at a time when the crystal structures
of even simple molecules was a great challenge. Her results changed
the face of modern biology. While working at Oxford University,
she was barred from research meetings of the faculty chemistry
club because she was a woman. Later, her talent and perseverance
prevailed and she won over the students and faculty members.
Dr. Hodgkin thought that it might be possible to determine the
insulin structure by working with an isomorphous crystal. An
isomorphous crystal is a derivative molecule where a single atom
is replaced by a heavier one. She believed the zinc atom to be
suitable for this type of manipulation. This was the beginning
of research that would take her 34 years to complete.
In 1937 she obtained her doctorate from Cambridge University.
Between 1942 and 1949 Dr. Hodgkin began work on the structural
analysis of penicillin. After the discovery of penicillin, some
of the best chemists in Britain and the United States were hard
at work trying to determine its chemical composition. She amazed
them all when she used X-ray analysis, not chemistry to determine
its structural arrangement. The structures of three derivatives
of benzylpenicillin (sodium, potassium, and rubidium) using isomorphous
replacement, optical analogs, and difference maps were determined.
Its structure was obscure until it was established by Dr. Hodgkin
and her colleagues in 1945. She also used the first IBM analog
computers to aid her in completing the X-ray calculations. This
was the first use of an electronic computer as applied to a biochemical
She determined that penicillin has an unusual ring structure with
at least four different forms and crystallizes in different ways.
This complexity causes it to be a difficult crystallographic
problem. Dr. Hodgkin insisted that its core consisted of three
rings of carbon atoms and a nitrogen atom. This 13-lactam structure
was assumed to be too unstable to exist independently. This was
the beginning of synthesis of chemically modified penicillin which
has helped to save many lives. Scientists were able to make chemical
modifications that were used as antibiotics (cephalosporins and
thiosterpton) which Dr. Hodgkin also helped to determine their
crystal structures. While completing her penicillin research,
Dr. Hodgkin was named a fellow of the Royal Society, Britain's
premiere scientific organization, in 1947.
Between 1948 and 1956 she continued to study at Oxford University
and Cambridge University. She became a Fellow and Chemistry Tutor
at Somerville at Oxford. As a tutor, she encouraged and guided
her fourth year and doctoral students towards interesting results
with crystal structures. One of her pupils later became well
known, not for her work in chemistry, but for her political work.
Margaret Thatcher worked as a fourth year student on X-ray crystallography
in Dorothy Hodgkin's laboratory. Despite later political differences
they always held a great affection for one another. While there
she also continued her X-ray analysis of complex biochemicals.
In 1955 she took the first X-ray diffraction photos of cyanocobalamin
crystals, obtained from Dr. Lester Smith of the Glaxo drug company;
more commonly known as Vitamin B-12. This organic molecule was
four times larger than penicillin. Until this point, normal chemical
methods had revealed little about the structure of the central
part of this molecule. They collected complete three-dimensional
data for four B-12 crystals: air-dried, wet, SeCN (having the
CN of B-12 replaced by SeCN), and a hexacarboxylic acid derived
from B-12. She began her analysis by locating the positions of
the heavy atoms, direct Patterson methods, and then calculating
the three-dimensional Fourier series using observed F values and
phases based only on the heavy atom's positions. Dr. Hodgkin pioneered
the use of Patterson maps. The results gave an approximation
as to the correct electron density series. Using these approximations
to obtain the correct electron density distribution, she was able
to determine the crystal structure of the hexacarboxylic acid
derived from B-12. Dr. Hodgkin used the cobalt atom to phase
the hexacarboxylic acid derivative of vitamin B-12 against the
advice of others. They all believed the scattering
power of the cobalt atom to be too weak with respect to the rest
of the molecule.
Dr. Hodgkin concluded that vitamin B-12 is a porphyrin, a type
of molecule related to chlorophyll, but with a cobalt center.
This porphyrin ring was missing one bridging carbon atom so that
the two pyrrole rings were directly linked, and the B positions
of these rings were each fully saturated. They found that the
molecule was spherical in form, contained chemical features not
seen before, and had a unique chemical structure. She also worked
with Kenneth Trueblood, a crystallographer with the University
of California at Los Angeles, because he had access to state of
the art computer equipment that helped to speed up the calculations
of the data. They used mail and telegraphs to communicate their
information between California and England. The atomic arrangement
of this molecule was eventually determined through the techniques
that she helped to develop.
It was later determined that this molecule was not the naturally
active vitamin and in 1961 they determined the structure of the
natural vitamin. This gave the hint at the biological structure
of the vitamin. This B-12 coenzyme was the first known naturally
occurring organometallic compound because of this cobalt-carbon
bond. This discovery later allowed for the vitamin to be synthesized
and used in the treatment and prevention of pernicious anemia.
Until this time, pernicious anemia was considered a deadly disease
until it was determined that it could be controlled by liver extracts.
These liver extracts can be produced synthetically from the same
mold that produces streptomycin. The active principle in liver
extracts, vitamin B-12, was isolated in crystalline form as a
deep-red cobalt-containing crystals. Vitamin B-12 is essential
to the building of red blood cells.
They also determined the structure of several related compounds
while researching this vitamin B-12. Their discovery was considered
"to be the most brilliant application of the X-ray crystallographic
approach" and lead to new areas within the field as to the
use of heavy atoms to determine the structures of biological macromolecules.
Because of her research, others were encouraged to tackle the
task of determining the structures of proteins.
In 1956 she received the Royal Medal. In 1958 she became a member
of the American Academy of Arts and Sciences. Between 1960 and
1977, Dr. Hodgkin was the first Royal Society Wolfson Research
Professor at Oxford University, an endowed chair financed by the
Royal Society. In 1961 Dr. Hodgkin began working with United
States crystallographer P. Galen Lenhert. Together they completed
the analysis of vitamin B-12 as it occurs in nature. They were
honored by Cambridge University for "playing a leading part
in determining by X-ray analysis the structure of penicillin and
vitamin B-12, the antidote to pernicious anemia." Dr. Hodgkin
was awarded an honorary doctorate by the university for her research.
In 1964 Dr. Hodgkin was awarded the Nobel Prize for Chemistry.
This was awarded for her research on the structure of vitamin
B-12. Dr. Hodgkin was only the third woman to ever win the Nobel
Prize in chemistry throughout the 63 year history of the award.
The other two were Madame Curie in 1911 and her daughter, Irene
Joliet-Curie in 1935. The award was given to her not only for
the determination of the structure of the vitamin B-12, but also
for the unprecedented discoveries which extended the bounds of
In 1965 she was named by Queen Elizabeth II as a member of the
Order of Merit. This is the United Kingdom's highest royal order.
Dr. Hodgkin was the first woman to be bestowed this honor since
On August 14, 1969, Dr. Hodgkin completed the deciphering of
the three-dimensional structure of the protein insulin. Insulin
research had always been her first love. This discovery was expected
to lead to an understanding of how it helps to lessen the symptoms
of diabetes. Dr. Hodgkin's research on the structure of insulin
was an adventure in persistence. It took her nearly 34 years
to complete her research which began in 1935. She never imagined
that this discovery would lead to practical applications. More
recently, genetic engineers have been able to change the chemistry
of insulin to improve its benefits for diabetics.
Insulin is amongst the smallest of all protein molecules because
it is only 51 amino-acid molecules long and is considered by research
scientists interested in the structures and biochemical functions
of molecules to be one of the most important. Dr. Hodgkin attacked
insulin crystals with X-rays. By measuring the intensity and
the direction of the scattered particles, she was able to map
the molecular configuration of the insulin molecule. She determined
the geometry of the 777-atom molecule. Dr. Hodgkin replaced the
zinc atoms in insulin obtained from pigs with atoms of three heavier
elements: lead, uranium, and mercury. After mapping the electron
densities of these three derivatives of insulin, the outline of
the molecule was computed, but they were not able to determine
the key sites for molecular activity through this research.
Dr. Hodgkin was able to determine that the insulin molecule is
a six-part molecule; roughly triangular in shape, consisting
of three pairs of molecules that enclose two zinc atoms within
the core. These are bound together at the ends by groups of pheylanine
(a specific amino acid) and secured midway by hydrogen bonds.
This six-part structure forms the natural insulin hormone.
The advancements in computer technology played a major role in
Dr. Hodgkin's ability to determine the structure of the insulin
molecule. In a 1977 interview with Peter Farago in the Journal
of Chemical Education, "In a larger molecular structure,
such as that of insulin, the way the peptide chains are folded
within the molecule and interact with one another in the crystal
is very suggestive in relation to the reactions of the molecules.
We can often see that individual side chains have more than one
conformation in the crystal, interacting with different positions
of solvent molecules around them. We can begin to trace the movements
of the atoms within the crystals." Her scientific endeavors
after this discovery revolved primarily around the refinement
of the structure of insulin and studies of its various forms.
In 1970 she was elected Chancellor of Bristol University. She
supported the establishment of the Hodgkin Scholarship, which
aided students from Third World countries, and founded Hodgkin
House which accommodated overseas students. Both were named for
her late husband who was a specialist in African studies. She
was one of the first chancellors to take an active interest in
the students and University events.
In 1971 she became a member of the United States National Academy
of Sciences and in 1972 she was given the Bakerian Lecture. From
1972 to 1978 Dr. Hodgkin was President of the International Union
of Crystallography. Her participation with this organization
caused Western governments some alarm because she insisted on
having crystallographers from behind the Iron Curtain participate
in conferences. Her affiliation with these types of organizations
caused her to have some problems with getting her entry visa to
the United States. As recognition for her work increased and
the Soviet Union disbanded, the restrictions on her United States
visa were finally lifted in 1990.
In 1976 Dr. Hodgkin received the Copley Medal from the Royal Society
and became a member of the USSR Academy of Sciences. In 1977
she officially retired, but continued to work on her causes for
world peace. Between 1977 and 1978 she was president of the British
Association for the Advancement of Science and in 1978 was awarded
the Longstaff Medal. Between 1977 and 1983 she was a fellow of
Wolfson College at Oxford. In 1982 she awarded the Lomonosov Gold
Medal because of her high standing within the Soviet scientific
community and in 1987 she was awarded the Lenin Peace Prize for
her commitment to the Soviet cause and her efforts towards easing
tensions between the East and the West while President of the
"Pugwash". She helped to form this group in 1976.
It was created to aid in the promotion of communication between
scientists on opposite sides of Iron Curtain during the Cold War.
During conferences on thermonuclear weaponry she was able to
cool heated discussions and tempers with a few gentle, thoughtful
words. In 1988 she became an honorary fellow at Bristol University.
In July of 1994, Dr. Dorothy Crowfoot Hodgkin died from stroke
at home in Shipston-on-Stour, England.
Dorothy Crowfoot was born in 1910 in Cairo, Egypt while both of
her parents were working there. Her father was an archaeologist
serving with the Egyptian Ministry of Education in Khartoum and
her mother was a self trained amateur on botany, nature artist,
and an expert on Coptic textiles. Her parents moved around the
world as her father's government career evolved and Dr. Hodgkin
and her sisters only saw them when they returned to England, which
was only for a few months each year. In 1914 she and her sisters
were left behind in England while their parents traveled to Egypt.
Dr. Hodgkin always said that this helped to encourage her independent
In 1937 she married Dr. Thomas Hodgkin who was an expert on African
affairs. He was the son of the late Robin H. Hodgkin provost
of Queen's College at Oxford and cousin to Professor A. L. Hodgkin
a recipient of the Nobel Prize for medicine in 1963. All of their
children took up their parents scholarly and nomadic habits.
Their eldest son Luke taught at the University of Algiers and
attended Princeton University in 1963 on a lectureship in mathematics.
Daughter Elizabeth taught at a girl's school in Zambia in 1964.
Son Tobias worked in India in 1964 in a volunteer service similar
to the American Peace Corps. In 1993 Dr. Hodgkin was a grandmother
nine times over, and had three great-grandchildren. Dr. Hodgkin
continued to travel extensively and touched every possible corner
of the world throughout her life despite her lifelong struggles
with rheumatoid arthritis that did not respond to treatment.
This eventually crippled her hands and feet, but despite this
she continued to travel and participate in her causes until the
The Hodgkin's were said to keep an open house where everyone was
always welcome and radiated warmth and hospitality. Their guests
included the powerful, the famous, revolutionaries and refugees,
as well as their own countless students, colleagues, and friends.
Over the years Dr. Hodgkin has worked with hundreds of scientists
from around the world and created an international joint family
where she acted as a motherly figure. Her "children"
include 25 from the United Kingdom, 20 from the United States,
10 from Australia, 7 from India, 6 from Canada, 5 from New Zealand
as well as others from Sweden, Switzerland, Italy, Chile, Denmark,
New Guinea, Germany, Holland, Yugoslavia, China, Japan, Poland,
France, Nigeria, and the former Soviet Union. To her students
and colleagues she "was a teacher, mother, friend, and guide
all rolled into one". She helped, advised, and encouraged
crystallographers and scientists she came into contact with.
Dr. Hodgkin has held close relationships with scientific communities
all over the globe. The scientific community in India, in 1973,
asked her to deliver the Azad Memorial Lecture. She has held
the Raman Professorship of the Indian Academy of Sciences and
was an honorary fellow of the Indian Academy of Sciences. She
has helped to promote international understanding through scientific
and related activities.
She has always been a champion of world peace and disarmament.
She was a strong supporter of national liberation struggles,
proponent of the development of third world countries, and signed
on with several organizations that admitted Communist party members.
Dr. Hodgkin inherited these ideals from her mother who was strongly
opposed to war because of the deaths of her four brothers. When
Dr. Hodgkin was a child her mother would take her to League meetings
Not only had she been a major contributor within her own field
of expertise, she tried to promote international goodwill and
understanding between all of the people throughout the world.
She has been described by colleagues as being a "warm, simple,
affectionate, and caring" human being.
In M. Vijayan's memorial written about her after her death, he
quoted Einstein as having said about Mahatma Gandhi: "Generations
to come, it may be, will scarce believe that such a one as this
ever in flesh and blood walked upon this earth." With all
of her accomplishments, awards, and contributions to modern science,
such can be said of Dorothy Crowfoot Hodgkin. One of her colleagues,
M. F. Perutz said of Dr. Hodgkin, "she will be remembered
as a great chemist, a saintly, gentle and tolerant lover of people
and a devoted protagonist of peace". Professor J. D. Bernal,
with whom Dr. Hodgkin conducted research, believed that successful
analysis depended on the researcher's strategy. He said of Dr.
Hodgkin, "She was one of these masters whose method of work
is as exciting and beautiful to follow as the results that flow
Dr. Hodgkin determined the molecular structures of penicillin, vitamin B-12, insulin, and countless other proteins through X-ray analysis. Through her research she was also able to improve the methods used in X-ray diffraction. She developed three-dimensional views of the molecular and atomic structures of extremely complex organic compounds, one more complicated and larger than the last. Her research allowed others to grow and expand their ideas. Two of which, Cambridge scientists John C. Kendrew and Max F. Perutz, were able to obtain clear, three-dimensional views of several proteins including hemoglobin and myoglobin. With each new discovery, Dr. Hodgkin expanded the technology of crystallography. By choosing projects others considered impossible, she helped to establish one of the characteristic features of contemporary science: the use of molecular structure to explain biological function.
"Hodgkin, Dorothy Crowfoot". The Grolier
Multimedia Encyclopedia. 1996 ed.
"Hodgkin, Dorothy Crowfoot". Concise
Columbia Electronic Encyclopedia. 1994 ed.
"Hodgkin, Dorothy Crowfoot". Compton's
Living Encyclopedia. 1996 ed.
Vijayan, M. "An Outstanding Scientist and Great Humanist: An Obituary of
Dorothy Hodgkin." Crystallography World
Wide. 20 September 1994.
Jaffe, Bernard. Crucibles: The Story of Chemistry
from Ancient Alchemy to Nuclear Fission. New York: Dover
Publications, Inc., 1976.
"Hodgkin, Dorothy Crowfoot". Facts
on File 54 (1994): 560.
"Insulin Structure Deciphered". Facts
on File 29 (1969): 783A.
"Nobel Prize Winner is a Grandmother."
The New York Times 30 Oct. 1964: 23.
"Hodgkin, Dorothy Mary, nee Crowfoot."
Larouse Dictionary of Scientists. 1994 ed.
Asimov, Isaac. Asimov's Biographical Encyclopedia
of Science and Technology. Doubleday and Company, Inc.: Garden
City, New York, 1972.
"Fifty Years of Pepsin Crystals," Nature
24 May 1984: 309.
"The Chemistry - Minded Mother," Time
6 Nov. 1964: 41.
"Insulin Design Traced," Science News
4 Oct. 1969: 307.
Mc Grayne, Sharon Bertsch. Nobel Prize Women
in Science. New York, New York: Birch Lane Press, 1993.
"Dorothy Crowfoot Hodgkin". Notable
Twentieth Century Scientists. 1995 ed.
"Hodgkin, Dorothy Crowfoot". Mc Graw
Hill Modern Scientists and Engineers. 1980 ed.
Glusker, Jenny P. and Margaret J. Adams. "Dorothy
Crowfoot Hodgkin." Physics Today May 1995.
Hodgkin, Dorothy Crowfoot. "The X-ray Analysis
of Complicated Molecules." Science 150 (1965): 979-88.
Copyright © 1996, Linda Juliana Cohen. All
rights reserved. Reprinted with permission.