Letter from Aaron Klug to Francis Crick DNA Nucleosomes Crystallography, X-Ray Klug here responded to Crick's comments on Klug's ideas about the spatial arrangement, or packing, of DNA and various histones (proteins associated with DNA) in crystals of DNA and particularly in nucleosomes, a specific complex of DNA and histones in the cells of higher organisms which under the electron microscope appear like beads on a string of DNA. Particularly, Klug and Crick debated the dimensions of the DNA helix in nucleosomes (measured in angstrom, or one ten-millionth of a millimeter), how the DNA helix might itself be coiled in a nucleosome, and how many base pairs were in each turn. Klug acknowledged that the theories of X-ray diffraction by a helix and by coiled coils (helixes that themselves are twisted, corkscrew-like) which he used in his studies of nucleosomes "are things I learnt at your knee, so to speak." Produced: 31 May 1977 The Wellcome Library for the History and Understanding of Medicine. Francis Harry Compton Crick Papers Klug, Aaron Letters (correspondence) Archival Materials Text 4 pages nlm:nlmuid-101584582X233-doc 101584582X233 http://resource.nlm.nih.gov/101584582X233 Profiles ID: SCBBQJ English Profiles in Science