Dissertation in Draft: Chapter VI

Date:: 1953

Reference:: PP/CRI/F/1/6

Catalogue details

Licence: In copyright

Credit: Dissertation in Draft: Chapter VI. Source: Wellcome Collection.

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This model can explain the simultaneous existence of both the 5.15 and the 1,5 Â reflect ions on the meridian. It also x broadly explains the equatorial reflexions, and probably the near x equatorial reflexions of African Porcupine Quill. The density calculated for this model is hearer the observed value, but it is still on the low side. Although the fibrous «¿-proteins all give the keratin pattern in the loose sense, they give it to varying degrees of perfection, African porcupine quill having sharp spots (McArthur I9I+3) whereas fiàszjëè of tropomysosin (Astbury, Reed & Spark 1948) given only a diffuse pattern. The more diffuse the °<ker atin ^becom es the more it resembles a very diffuse pattern fronts patternj^fi'um a synthetic polypeptide, that is, a diffuse -helix to y+£- pattern. It seems^unlikely &e=me that the diffuse oL -keratin patterns are all disordered versions of exactly the same structure. It is more probably that their similarity reflects a general type of structure, which I believe to be ©¿-helices arranged in a non- ( /ß<v ■') parallel manner for reasons of packing. It is unlikely that uáJÍZ. tropomyosin for example, which may well be only two o¿ -helices has the detailed structure proposed tyPauling & Corey, which has been based on data from African porcupine quill.

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