Dear Dr. Pauling
I have discovered three more satisfactory helices. In the notation of Bragg, Kendrew
and Perutz, these are 3.010, 4.414, and 4.416. They have 2.00, 1.20 and 1.15 Å per residue along z. I suspect that 4.416 is the π of Barbara Low, but her description, unfortunately, fits both 4.414 and 4.416. 4.414 is somewhat strained (angle at α-carbon=102 degrees, and each residue is twisted
6 degrees [0.4 Kcal/mole/residue]), 4.416 is planar, but α-carbon angle is 114 degrees. This could probably be decreased a
little. 3.010 is entirely satisfactory. I have written to Barbara for clarification, and when
I get it, I am going to write these up, and will send you a copy before I submit it
anywhere. I think it should be a letter to the editor of J.A.C.S.
I am also calculating radial distribution functions, in order to test the sensitivity
of the method. I do not check your curves for the α-helix. Would it be possible
for you to have a copy made of the list of interatomic distances (i.e., kind and length)
so that I can see what went wrong?
I got another letter from Prof. Stanley in which he is rather more hopeful, but would
rather talk things over with me personally. In as much as I should much prefer to locate in California rather than anywhere else, and since negotiations
at this distance for any position are rather difficult, I am wondering if it would
not be better for me to come back to Crellin for a year before taking a permanent
place. You mentioned this possibility in one of our talks last spring, and I must
confess it looks more attractive to me now than it did then.
Francis Crick's α-keratin letter appeared in the Nov. 22 Nature. it is now three
issues later and yours is not out yet. I do not know any reason for the delay, but
Francis is rather embarrassed by it, as he assumed the two letters would appear together.
I believe that he is going to write you about it.
Arndt and Riley have found a 1.5 Å reflection in some oriented fibrous insulin which
Freddie Gutfreund gave them. It will take some checking before they're sure, though.
They have put all manner of proteins in their radial distribution machine, and are
now chewing on the results. We hope to learn them shortly.
I enclose a drawing of the 3.010, which I should like returned.