Double take

"I am now astonished that I began work on the triple helix structure, rather than on the double helix," wrote Linus Pauling in the April 26, 1974 issue of Nature.

In February 1953, Pauling proposed a triple helix structure for DNA in the Proceedings of the National Academy of Sciences (PNAS). He had been working with only a few blurry X-ray crystallographic images from the 1930s and one from 1947. If history's helix had turned slightly differently, however, perhaps the following timeline might be more than mere musing…

August 15, 1952: Linus Pauling (finally allowed to travel to England by a US State Department that thinks the words "chemist" and "communist" are too close for comfort) visits King's College London and sees Rosalind Franklin's X-ray crystallographs. He immediately rules out a triple helical structure for DNA and concentrates on determining the nature of what is undoubtedly...