March 20, 1953
Dear Dr. Pauling
I enclose a copy of the helical paper. You will note that I now include the αII ribbon among the possible structures. I found the version in the paper in a very curious way: I set out to prove analytically
that it couldn't be built, and as I rotated the two residues the hydrogen bond gradually became "satisfactory!" I hope we
have time to discuss this when you are here next month, unless you wish to send it off to the PNAS straight away.
Watson and Crick have constructed a very ingenious nucleic acid structure which they have written (but not sent) a letter
to Nature about. They will send you a copy at the beginning of next week, as Bragg is now ill with flu, and they feel he
should see it before they send it anywhere. I have become (actively) interested in this problem myself, although I find I
lack the necessary background, a situation which I am now remedying.
Have you heard any more about the grant for the nucleic acid program that you mentioned in your letter to me on December 23,
as I should certainly appreciate the "definite offer" you wrote of, as I do not have any other firm prospects at the moment.
The EDSAC is at present being overhauled. When that job is finished I hope to be able to run off the three Pattersons on
sheep Hb, as the experimental part is finished. I do not think this will be done until the end of next month, though.
P. S. The reason that the CS2S6 structure in the February Acta still shows the alternating S-S distances is that the parameters differ from those in the
MIT report you had. They differ in such a way as to preserve the alternation when the correct conversion from triclinic to
orthogonal coordinates is made.