What incorrect DNA model did Linus Pauling publish in early 1953?

The incorrect DNA model Linus Pauling published in early 1953 was a triple helix.

Pauling, already famous for explaining the protein alpha helix, proposed that DNA consisted of three intertwined chains. His February 1953 paper placed the phosphate groups toward the center and the bases on the outside. The arrangement was chemically unsound, especially because it treated DNA’s acidic phosphate groups in an implausible way.

The mistake mattered because Watson and Crick knew Pauling was also competing to solve DNA’s structure. Once they learned that Pauling had published a model, they examined it and recognized problems that helped clarify what a successful structure could not look like. Evidence from Rosalind Franklin, Maurice Wilkins, and other researchers also pointed toward a double-helical arrangement.

Watson and Crick published the correct two-stranded model in *Nature* on April 25, 1953. “Beta sheet” belongs to protein structure, while quadruple- and single-stranded nucleic-acid structures are distinct concepts, not Pauling’s famous 1953 proposal.