Comment by dnautics
3 days ago
what? she was doing a form of crystallography that ONLY makes sense if it's a helix? Like, any time you are doing fiber diffraction it's pretty much "a helix". Who claimed she didn't realize it was a helix? I thought the claim was that she didn't recognize the significance of the helical parameters, which of course she couldn't, she wasn't a chemist and didn't have a model in mind with knowable parameters.
She might have measured those parameters, but she still didn't know what she had (as evidenced by how she subsequently spent a ton of time on Z-dna)
> which of course she couldn't, she wasn't a chemist
Actually, of all of the characters involved, she was the only chemist. Watson was a biologist, Crick was a physicist, as was Wilkins. That's why Franklin was ultimately brought in: to make further progress, they needed a chemist with crystallography experience, and Franklin was the one who had that experience.
I beleive fibre diffraction also works on parallel fibres (non-helical). For example, long chains of beta-sheet (look at beta keratin, which is one of the early non-helical structures analyzed by Astbury).
Technically beta keratin is helical. That said you are correct, there is no requirement to be helical for fiber diffraction. It just turns out it's very difficult to have non helical uniaxial symmetry in nature.
When I was studying spindle shaped viruses by electron microscopy we'd get beautiful fiber diffraction patterns in the fourier transform of the micrographs. I always wanted to try and solve the helical parameters but never got around to it.
Beta keratin fibers are helical. (The pitch is much longer, but still helical, not alpha helices obvs).
The point of the article is not to provide new information.
The point of the article is to create the impression in the reader that Franklin did everything of any importance and was robbed of credit by the white men riding her coattails.
It will work.