Linus Pauling and the Structure of Proteins: A Documentary History Narrative  
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On his fiftieth birthday, Feb. 28, 1951, Pauling mailed a manuscript, "The Structure of Proteins: Two Hydrogen-Bonded Helical Configurations of the Polypeptide Chain" to the Proceedings of the National Academy of Sciences (PNAS) It was the expanded version of the note he and Corey had published four months earlier, this time adding Herman Branson's name. It was a detailed description of the alpha and gamma helixes.

A few days later, Pauling wrote Weaver, "The difference between our two predicted configurations and others that have been described in the literature is that ours are precise, whereas the others are more or less vague." This much was true. But Pauling's next statement – "I feel in a sense that this represents the solution of the problem of the structure of proteins." – would prove wildly inaccurate. Weaver, for his part, saw the paper as a justification of his years of support for Pauling's protein research. He dispatched a science writer and publicist named George Gray to Pasadena to prepare a full report for the Rockefeller trustees.

Pauling also gave a heads-up to the editor of a popular science magazine, Scientific American, pushing for publicity even before his paper appeared in print, writing, "It seems to me to be just about the most important step forward that has been made during the last 25 years or perhaps 50 years in this field." The editor quickly replied, asking for more details about Pauling's "bombshell," and asking him to write an article about it for the magazine.

By then, however, Pauling was deeply engrossed in more protein work. It was as though sending in the paper on the helixes freed him to finalize his other ideas. Through March and into April, he and Corey feverishly finalized their ideas for a half-dozen more protein structures. "I am having a hard time keeping my feet on the ground now," he wrote a former student in mid-March. "I have been working night and day, neglecting almost everything else."

On April 1, the Pauling, Corey, and Branson paper on the alpha and gamma helixes was published in PNAS. It proved a turning point in the history of molecular biology. Upon reading it, Sir Lawrence Bragg rushed to the nearby laboratory of Alexander Todd, an expert in organic chemistry, to ask if indeed the peptide bond was planar, as Pauling insisted. "I told him," remembered Todd, "if he had asked me at any time in the past ten years, or if he had asked anybody in my lab, we could have told him that the peptide bond had to be planar." If the peptide bond was planar, Bragg realized, there was a very good chance that Pauling's alpha helix was right. Bragg was a physicist. He now saw that he had lost a race because he had overlooked some facts of chemistry. Todd said Bragg was "horrified" when he heard the news, and swore from that point on never to allow anything to be published by his protein group again until they got Todd's okay on the chemistry of their structures.

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Audio Clip  Audio: Misunderstanding Planarity. October 14, 1992. (0:45) Transcript and More Information

See Also: Letter from Linus Pauling to Dennis Flanagan. March 8, 1951. 
See Also: Letter from Linus Pauling to E. Bright Wilson, Jr. March 15, 1951. 
See Also: The structure of proteins: Two hydrogen-bonded helical configurations of the polypeptide chain. April - May 1951. 

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Linus Pauling and Lord Alexander R. Todd. Cambridge, England. 1948.

Page 1
"The Structure of Proteins: Two Hydrogen-Bonded Helical Configurations of the Polypeptide Chain." February 28, 1951.

"Todd says that he told Bragg that the amide group was planar, but apparently Bragg did not understand what he said. I was fortunate in having a good understanding of two fields, structural chemistry and x-ray diffraction. My recommendation to young scientists is that they get a thorough knowledge of one field, and also some knowledge of other fields of science."

Linus Pauling
January 12, 1993
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