Francis Crick his skills in the analysis of X-ray diffraction data for proteins, working primarily on ribonuclease and the mechanisms of protein synthesis. David Harker, the American X-ray crystallographer, was described as "the John Wayne of crystallography" by Vittorio Luzzati, a crystallographer at the Centre for Molecular Genetics in Gif-sur-Yvette near Paris, who had worked with Rosalind Franklin. After the discovery of the double helix model of DNA, Crick's interests quickly turned to the biological implications of the structure. In 1953, Watson and Crick published another article in "Nature" which stated: "it therefore seems likely that the precise sequence of the bases
Non-helical models of DNA structure Non-helical models of DNA structure In the history of molecular biology, non-helical or "side-by-side" models of DNA were proposed in the 1970s as a challenge to the standard double-helical model. The non-helical models attempted to solve problems relating to the topology of circular DNA chromosomes during replication. These theories were briefly considered seriously as a minority viewpoint, but they were later largely rejected due to X-ray crystallography of DNA duplexes and later the nucleosome core particle, as well as the discovery of topoisomerases, and these non-double-helical models are not currently accepted by the mainstream scientific community. The strands of a