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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 SURPRISE. “The resultant structure was quite unusual. It was a left-handed helix. However, it was not a simple left-handed helix, but one in which the alternating purine-pyrimidine sequence of the oligonucleotide was used in a unique way.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

STABILIZED CRYSTALS. “It was discovered that crystals could be formed readily using magnesium and spermine as cations. Furthermore, these crystals diffracted to 0.91 resolution.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

FIRST MILESTONE. “The first visualization of the double helix at atomic resolution occurred almost ten years ago with the solution of the structures of rApU and rGpC which were found to form right-handed double helical fragments of the type which had been anticipated for RNA molecules.” (1982). https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

TECHNICAL RESOLUTION. “Unlike fiber diffraction patterns, single crystals can diffract to a very high resolution and they produce very large numbers of reflections or experimental measurements. This in turn makes it possible to solve the structures and observe fine details of DNA conformation in which very little or no interpretation is required.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

PURE CRYSTALS. “The recent development of chemical methods for synthesizing DNA made it possible to produce oligonucleotides in amounts great enough for crystallization experiments.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn