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An Early X-ray Pioneer Finally Gets Her Due
By Heather Rock Woods
In 1952,
Rosalind Franklin (King’s College London) made key images of DNA that
contributed to the discovery of the double helix structure of DNA by James
Watson and Francis Crick. The two men received the 1962 Nobel Prize, but they
gave no credit to her pivotal images and data—which they had seen without her
permission or knowledge.
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Lynne Osman
Elkin, foreground, (CSU, East Bay) gave the March WIS seminar on
the pivotal DNA x-ray crystallography work done by Rosalind
Franklin. |
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Photo by Diana Rogers |
The speaker at last month’s Women’s Interchange at SLAC (WIS) celebrated
Franklin’s crucial role in one of the most significant scientific
triumphs in the last century. Lynne Osman Elkin, Professor Emeritus of
Biological Sciences at CSU East Bay, is writing a biography on Franklin.
Elkin has also appeared in a NOVA documentary on Franklin’s work (which
WIS aired on March 14) and published an article on her in Physics Today
in March 2003 (http://www.aip.org/pt/vol-56/iss-3/p42.html).
Franklin was a British
chemist, an x-ray diffraction expert, and a superb experimentalist.
“From 1953 to 1968 she was essentially written out of DNA history,”
Elkin said.
Her reappearance in the DNA
chronicles—in Watson’s 1968 book The Double Helix, 10 years after her
death—didn’t do her justice.
“According to Watson’s
book, she is an obnoxious assistant who gets data, won’t give it to her
boss, holds up the progress of science and is incompetent at
interpreting her own data. That’s their rational for appropriating her
data,” Elkin said.
It ultimately took the combined efforts of many theoretical and
experimental scientists to solve the structure. The structural
arrangement of DNA was a great puzzle: how could such a seemingly simple
molecule, made up of just four different types of nucleotides, encode
all the directions to tell living things to grow and reproduce?
Franklin’s work shares
the same underlying principals as the protein crystallography work now
done at SSRL. Proteins, and occasionally DNA, are crystallized to make
x-ray diffraction patterns that reveal the structure of large, intricate
molecules.
“She was a pioneer in
crystallography,” said Ana Gonzalez (ESRD). “The kind of analysis she
used is still routinely used today to find heavy atoms in proteins and
in DNA.”
SSRL has been a modern pioneer in
crystallography methods, and allocates more than a fifth of its beam
time to crystallography studies—which play an important role in drug
design. “A big difference today is we have much better x-ray sources,”
Gonzalez said. “There are differences in the diffraction by proteins,
which form well-ordered crystals so you get sharp spots, and the
diffraction by DNA, which is more like blobs.”
Half a century ago,
making x-ray diffraction patterns of DNA was very difficult, but
Franklin was experienced, and a perfectionist. According to Elkin,
Franklin spent so much time aligning the x-ray beam perfectly to her
samples that it may have contributed to her early death from ovarian
cancer at age 37.
Franklin came to King’s College in
London in 1951, just seven years after the first clear proof that DNA
was the genetic material of life. Relations between Franklin and her new
colleague, Maurice Wilkins, got off to a bad start when the head of the
lab betrayed Wilkins by giving his project to Franklin.
“They couldn’t stand
each other,” Elkin said. “They had diametrically opposite personalities
(she was prickly, he was shy), and the head of the lab was a disastrous
interpersonal manager.”
Wilkins shared the
1962 Nobel for confirming the structure with his x-ray studies between
1953 and 1959. But before the discovery and confirmation, he shared
Franklin’s unpublished data and images with Watson and Crick without her
knowledge.
In 1952, Franklin prepared DNA fibers
and directed her graduate student, Raymond Gosling, to make a
diffraction image of the fibers—the famous Photo 51. The image’s X
pattern was evidence of a helix, and contained vital information on the
distance between atoms and the distance between the repeating pattern of
the molecule (DNA’s two strands are like the banisters on a spiral
staircase). At the end of the year she wrote up much of her new data and
analysis in an internal report.
Wilkins showed Photo
51 to Watson and Crick at the end of January 1953 and told them about
the internal report, which they managed to acquire through their
contacts. “In January 1953, where were Watson and Crick without her
data? Nowhere,” said Elkin. “At the same time, she was very close to the
solution.”
In fact, Elkin said, Crick later estimated Franklin was herself three
weeks to three months away from solving the structure of DNA. Her data,
combined with strong theoretical suggestions from their colleague Jerry
Donohue, made possible Watson and Crick’s correct model in early March
1953. In their Nobel speeches four years after Franklin died, neither
Watson nor Crick mentioned her, while Wilkins succinctly acknowledged
that she made “valuable contributions.” Elkin wants to show the world
how truly valuable these contributions were. She is striving to clarify
and bring due recognition to Franklin’s essential part in the brilliant
illumination of the elegant structure of DNA. |
