Protein studies, while important to Pauling, comprised only a fraction of his work
during the late 1940s and early 1950s. He was overseeing a large, bustling laboratory
where visiting fellows, postdocs, assistants, and graduate students were studying
a variety of questions, from chemical bonds to antibodies, the structure of inorganic
molecules to the nature of metals. Pauling was also penning influential textbooks
(General Chemistry in 1949 and College Chemistry in 1950); serving a year as President of the American Chemical Society; speaking
widely on chemical topics; and spending an increasing amount of time giving speeches
on peace and nuclear proliferation (as well as dealing with the personal and professional
fallout from speaking out, often against US government policy).
Amid all the activity, however, during a few months in the spring and summer of 1950
Pauling focused his mind on protein structures. The impetus was publication of the
grab-bag of ribbons and spirals by Bragg's group, in a paper that Bragg later regretted
publishing. Pauling, not wanting to be beaten to a detailed solution of the keratin
structure, threw himself back into the race, reading widely, thinking about his own
past attempts, and carefully reviewing Branson's two helixes. These two structures,
the alpha and gamma helixes, looked increasingly attractive and compelling as Corey
went through the painstaking process of checking and refining them. Pauling and Corey
came to believe in the structures. But that was only the beginning. The helixes served
as a starting point for thinking about other structures besides keratin. Pauling and
Corey played with stretching the helixes, flattening them into a sort of pleated sheet,
a structure that very much resembled silk. They started modeling more complex proteins
like collagen and feather rachis.
There was still one major drawback, however: Neither of the helixes matched the 5.1
angstrom repeat that showed up in all of Astbury's x-ray patterns from keratin. The
alpha helix, which came closest, made a turn every 5.4 angstroms. No matter how much
he tried to reshape his helixes, Pauling could find no chemically reasonable way to
make his models match the x-ray data.
That is where most chemists would have stopped. In a battle between experimental results
and theory, experiment wins, every time. Theory has to match experimental results
(or a reasonable, testable reason must be put forward to explain the discrepancy)
– that's the way the game is played. By these rules, Pauling's theoretical helixes
should have remained unpublished.
Instead, feeling "forced into it by the Bragg, Kendrew, and Perutz paper," Pauling
decided to ignore the contradictory evidence from the x-ray studies of keratin, and
to publish anyway. On October 16, 1950, Pauling and Corey sent a short note to the
Journal of the American Chemical Society saying that they had come up with two spiral models, mentioning their hydrogen bonding
scheme, and asserting that there was evidence that the proposed structures were present
in a variety of proteins. They hinted at a molecular model for silk. They said nothing
about the discrepancy between their models and the x-ray data. They ended with the
promise that "a detailed account of this work will be published soon."
Pauling and Corey were sure enough of their ideas to take a chance and establish scientific
priority, in essence saying, "We're first with this idea." Then they went back to
work trying to shore it up.