Max Perutz the onset of Huntington disease is related to the number of glutamine repeats as they bind to form what he called a polar zipper. During the early 1950s, while Watson and Crick were determining the structure of deoxyribonucleic acid (DNA), they made use of unpublished X-ray diffraction images taken by Rosalind Franklin, shown at meetings and shared with them by Maurice Wilkins, and of Franklin's preliminary account of her detailed analysis of the X-ray images included in an unpublished 1952 progress report for the King's College laboratory of Sir John Randall. Randall and others eventually criticised the manner in which
Francis Crick before Pauling was able. Franklin's X-ray diffraction data for DNA and her systematic analysis of DNA's structural features was useful to Watson and Crick in guiding them towards a correct molecular model. The key problem for Watson and Crick, which could not be resolved by the data from King's College, was to guess how the nucleotide bases pack into the core of the DNA double helix. Another key to finding the correct structure of DNA was the so-called Chargaff ratios, experimentally determined ratios of the nucleotide subunits of DNA: the amount of guanine is equal to cytosine and the amount