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
