Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid ; Molecular Structure of Deoxypentose Nucleic Acids ; Molecular Configuration in Sodium Thymonucleate . Three papers in a single offprint from Nature, Vol. 171, No. 4356, April 25, 1953

'Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid'; 'Molecular Structure of Deoxypentose Nucleic Acids'; 'Molecular Configuration in Sodium Thymonucleate'. Three papers in a single offprint from Nature, Vol. 171, No. 4356, April 25, 1953

First edition. DISCOVERY OF THE STRUCTURE OF DNA. First edition, in the rare offprint form, of one of the most important scientific papers of the twentieth century, which "records the discovery of the molecular structure of deoxyribonucleic acid (DNA), the main component of chromosomes and the material that transfers genetic characteristics in all life forms. Publication of this paper initiated the science of molecular biology. Forty years after Watson and Crick's discovery, so much of the basic understanding of medicine and disease has advanced to the molecular level that their paper may be considered the most significant single contribution to biology and medicine in the twentieth century" (One Hundred Books Famous in Medicine, p. 362). "The discovery in 1953 of the double helix, the twisted-ladder structure of deoxyribonucleic acid (DNA), by James Watson and Francis Crick marked a milestone in the history of science and gave rise to modern molecular biology, which is largely concerned with understanding how genes control the chemical processes within cells. In short order, their discovery yielded ground-breaking insights into the genetic code and protein synthesis. During the 1970s and 1980s, it helped to produce new and powerful scientific techniques, specifically recombinant DNA research, genetic engineering, rapid gene sequencing, and monoclonal antibodies, techniques on which today's multi-billion dollar biotechnology industry is founded. Major current advances in science, namely genetic fingerprinting and modern forensics, the mapping of the human genome, and the promise, yet unfulfilled, of gene therapy, all have their origins in Watson and Crick's inspired work. The double helix has not only reshaped biology, it has become a cultural icon, represented in sculpture, visual art, jewelry, and toys" (Francis Crick Papers, National Library of Medicine, profiles./SC/Views/Exhibit/narrative/). In 1962, Watson, Crick, and Wilkins shared the Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material." In 1869, the Swiss physiological chemist Friedrich Miescher (1844-95) first identified what he called 'nuclein' inside the nuclei of human white blood cells. (The term 'nuclein' was later changed to 'nucleic acid' and eventually to 'deoxyribonucleic acid,' or 'DNA.') Miescher's plan was to isolate and characterize not the nuclein (which nobody at that time realized existed) but instead the protein components of leukocytes (white blood cells). Miescher thus made arrangements for a local surgical clinic to send him used, pus-coated patient bandages; once he received the bandages, he planned to wash them, filter out the leukocytes, and extract and identify the various proteins within the white blood cells. But when he came across a substance from the cell nuclei that had chemical properties unlike any protein, including a much higher phosphorous content and resistance to proteolysis (protein digestion), Miescher realized that he had discovered a new substance. Sensing the importance of his findings, Miescher wrote, "It seems probable to me that a whole family of such slightly varying phosphorous-containing substances will appear, as a group of nucleins, equivalent to proteins". But Miescher's discovery of nucleic acids was not appreciated by the scientific community, and his name had fallen into obscurity by the 20th century. "Researchers working on DNA in the early 1950s used the term 'gene' to mean the smallest unit of genetic information, but they did not know what a gene actually looked like structurally and chemically, or how it was copied, with very few errors, generation after generation. In 1944, Oswald Avery had shown that DNA was the 'transforming principle,' the carrier of hereditary information, in pneumococcal bacteria. Nevertheless, many scientists continued to believe that DNA had a structure too uniform and simple to store genetic information for making complex living organisms. The genetic material, they reasoned, must consist of proteins, much more diverse and intricate molecules known to perform a multitude of biological functions in the cell. "Crick and Watson recognized, at an early stage in their careers, that gaining a detailed knowledge of the three-dimensional configuration of the gene was the central problem in molecular biology. Without such knowledge, heredity and reproduction could not be understood. They seized on this problem during their very first encounter, in the summer of 1951, and pursued it with single-minded focus over the course of the next eighteen months. This meant taking on the arduous intellectual task of immersing themselves in all the fields of science involved: genetics, biochemistry, chemistry, physical chemistry, and X-ray crystallography. Drawing on the experimental results of others (they conducted no DNA experiments of their own), taking advantage of their complementary scientific backgrounds in physics and X-ray crystallography (Crick) and viral and bacterial genetics (Watson), and relying on their brilliant intuition, persistence, and luck, the two showed that DNA had a structure sufficiently complex and yet elegantly simple enough to be the master molecule of life. "Other researchers had made important but seemingly unconnected findings about the composition of DNA; it fell to Watson and Crick to unify these disparate findings into a coherent theory of genetic transfer. The organic chemist Alexander Todd had determined that the backbone of the DNA molecule contained repeating phosphate and deoxyribose sugar groups. The biochemist Erwin Chargaff had found that while the amount of DNA and of its four types of bases the purine bases adenine (A) and guanine (G), and the pyrimidine bases cytosine (C) and thymine (T) varied widely from species to species, A and T always appeared in ratios of one-to-one, as did G and C. Maurice Wilkins an. Nº de ref. del artículo: 6370

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