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Linus Pauling Reports the First Discovery of a Helical Structure for a Protein

Alpha-Helix computer graphic from the Wikipedia.

Alpha-Helix computer graphic from the Wikipedia.

On his fiftieth birthday, February 28, 1951, American physical chemist Linus Pauling reported with his co-workers at Caltech, the American biochemist Robert Corey and the African-American physicist and chemist Herman Branson, the discovery of the alpha helix (α-helix). This was the first discovery of a helical structure for a protein. Their discovery built upon and confirmed the research of William Astbury reported in 1931.

"Although incorrect in their details, Astbury's models of these forms were correct in essence and correspond to modern elements of secondary structure, the α-helix and the β-strand (Astbury's nomenclature was kept), which were developed by Linus Pauling, Robert Corey and Herman Branson in 1951; that paper showed both right- and left-handed helixes, although in 1960 the crystal structure of myoglobin showed that the right-handed form is the common one. . . .

"Two key developments in the modeling of the modern α-helix were (1) the correct bond geometry, thanks to the crystal structure determinations of amino acids and peptides and Pauling's prediction of planar peptide bonds; and (2) his relinquishing of the assumption of an integral number of residues per turn of the helix. The pivotal moment came in the early spring of 1948, when Pauling caught a cold and went to bed. Being bored, he drew a polypeptide chain of roughly correct dimensions on a strip of paper and folded it into a helix, being careful to maintain the planar peptide bonds. After a few attempts, he produced a model with physically plausible hydrogen bonds. Pauling then worked with Corey and Branson to confirm his model before publication. In 1954 Pauling was awarded his first Nobel Prize "for his research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances" (such as proteins), prominently including the structure of the α-helix" (Wikipedia article on Alpha helix, accessed 01-17-2014).

Pauling, Corey, and Branson, “The Structure of Proteins: Two Hydrogen-Bonded Configurations of the Polypeptide Chain," Proceedings National Academy of Sciences 37 (1951) 205-11.

Judson, The Eighth Day of Creation, 88-89.

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