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LEVOROTATORY VARIANT. “Although there was discussion of the possibility of left-handed helices, especially shortly after the double helix formulation, there were very few systematic studies of left-handed helices published during the next decade or so.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

THE VARIANTS. “The greater wealth of diffraction data seen in the A pattern made it possible to get more information. The relative ease with which it slipped into the B pattern reinforced the idea that these were two conformational variants; it was found that both patterns could be fitted by a right-handed double helix.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

METHODOLOGICAL LIMITATIONS. “Considerable attention was paid to the fact that under certain conditions alternative conformational variants were seen. The most important of these was the A-DNA pattern which originally was produced by air-dried fibers.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

THE MANTRA. “One assumption was that the structure was perfectly regular with an asymmetric unit consisting of one nucleotide. However, the agreement was reasonable and this led to the general adoption of the right-handed B-DNA conformation as the predominant form in biological systems.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

THE PROBLEM. “The X-ray diffraction patterns were limited, and far from atomic resolution. Because of the limited resolution the patterns had to be interpreted and a number of assumptions made.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

SLOPPY DATA. “It was obvious to workers in the field, however, that although DNA fiber analysis generated physical data in agreement with the Watson-Crick structure, they did not unambiguously prove the structure.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

DEXTROROTATORY MODIFICATION. “Efforts spanning over a decade produced a great deal of experimental evidence which in essence stated that it was possible to modify the initial Watson-Crick right-handed helix in a number of details so that one could produce a model consistent with the experimental X-ray data.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

CHIRALITY. “DNA can have both right-handed and left-handed double helical conformations. This idea has old roots and was considered shortly after the formulation of the double helix by Watson and Crick in 1953.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn