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Letter from W.L. Bragg to Linus Pauling. May 5, 1952.
Bragg writes to express his feeling of the "essential correctness" of the alpha-helix model, though others at the Royal Society meeting voiced their doubts. Bragg also provides details of his and Max Perutz's latest "frontal attack" on the structure of helioglobin.


Cavendish Laboratory, Cambridge.

5th May 1952

Dear Pauling,

We are all very sorry indeed that you could not come to the Royal Society discussion, and in fact the meeting we all felt lost most of its point because you were not there. We also looked forward so much to your visit to Cambridge.

There was much discussion about your model of the α helix; a number of people are still doubtful about it and you ought to have been there to answer their questions personally. I am convinced of its essential correctness. It may be twisted or untwisted a bit from the exact form you propose, but that is merely a minor detail. It seemed to me that the existence of something very like it in the artificial polypeptides, at any rate, is very strongly confirmed.

Perutz and I have been making a frontal attack on the structure of the helioglobln molecule. I am no biochemist and have felt my best contribution is to see what one can deduce purely by X-Ray Analysis without making any assumptions about the structure of the molecule. We are not there yet, but I think we have got a long way. In the (hol) projection which is centrosymmetrical the different shrinkage forms enable one to plot many values of F(hol) along the h = constant layer lines. We have so many points that we are able to establish the nodes and loops along these layer lines and of course we know they alternate + and - in sign. If we can take the further step of relating the signs of each layer line to the next we can then make a Fourier picture of the crystal. We have not made this further step yet but have hopes of doing so. We can already relate layers one and two to the central layer and are working hard to do the rest.

We have some interesting work on living muscle also which I should have enjoyed showing you. This is being done by young Huxley who is coming to MIT as a Commonwealth Fellow in September 1952.

We shall look forward to having your son here, you must try and pay another visit while he is here.

With warm regards,

Yours sincerely,

Professor L. Pauling

California Institute of Technology, Pasadena 4

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