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Showing papers in "Acta Crystallographica in 1953"


Journal ArticleDOI
TL;DR: In this paper, the two-strand rope and three-stranded rope models were described and used to illustrate the diffraction theory already developed, and it was shown that they would give a diffuse pattern.
Abstract: It is shown in this paper by Crick that when -helices of the same sense pack together they will probably do so about 20° away from parallel. For very long chains this may lead to a coiled-coil. The two simplest models - the two-strand rope and the three-strand rope - are described, and used to illustrate the diffraction theory already developed. It is shown that they would give a diffuse -pattern. Possible examples of these models are briefly discussed.

1,518 citations



Journal ArticleDOI
TL;DR: A qualitative survey by Franklin & Gosling of the types of X-ray diagram given by highly orientated specimens of NaDNA at different humidities is reported in this paper, which suggests that the fundamental structural unit is a group of molecules so arranged that the phosphate groups are exposed and accessible to water.
Abstract: A qualitative survey by Franklin & Gosling of the types of X-ray diagram given by highly orientated specimens of NaDNA at different humidities is reported. The structural changes which occur in NaDNA fibres when their water content is varied suggest that the fundamental structural unit is a group of molecules so arranged that the phosphate groups are exposed and accessible to water.

345 citations





Journal ArticleDOI
TL;DR: In this paper, the effect of salt substitution in the birefringenee is calculated and compared with Perutz's observations, and the optical data indicated a more elongated molecule (a/b,-~ 1.45) than that deduced from the X-ray data (a /b,.
Abstract: Perutz has shown that the birefringence changes when the water in a haemoglobin crystal is replaced by salt solution. The effect of this substitution in the birefringenee is calculated and compared with Perutz's observations. There is agreement as to the order of magnitude of the effect, but the optical data indicated a more elongated molecule (a/b ,-~ 1.45) than that deduced from the X-ray data (a/b ,.~ 1.3). This discrepancy is not to be stressed, since the form of the molecule is not yet certain and the measurements of change in birefringence are very approximate. A further exploration of the effect may yield a useful method of estimating the form of other protein molecules.

248 citations