22nd June, 1951
Dear Pauling,
I am very glad to hear about the clearing up of the difficulty about the copper-tin
compounds. I have not actually heard from Dr. Shoemaker but I would like to get his
account of the structure and to understand how the different arrangements of the atoms
accounts for the two forms.
I quite agree that I had in my speech overlooked the Dickinson & Raymond paper of
1922, though I did know of the structure I thought it seemed so long ago, actually
before I took up the subject myself, that I had rather treated it as one of the facts
of nature.
Actually the hexamethyl-enetetramine structure was quite a special one. Practically
unparalleled except in adamantane in crystal structure and therefore the real importance
was that Robinson had developed a general method applicable to all unknown structures.
I read your papers with Corey with the greatest interest and I certainly think that
you have made the point that it is not necessary that the residues should follow each
other along the chain with any regular crystallographic repeats. On the other hand,
I am rather doubtful on the basis of Carlisle’s work here, that any structure with
as many as 3, let alone 3.7, residues per turn can be fitted into the data for some
crystalline proteins such as ribonuclease and chymotrypsin. The number we get by estimation
of the number of chains and the periodicities along the chain, in this case about
5.4 A, indicates a figure much more like 2.
I am extremely sorry that you are not going to be at Stockholm and even more so that
you won’t be at the Protein Conference that we are holding at Cambridge after it,
because I feel that your point of view based on the theoretical chemical information
is an essential contribution to the unraveling of the problem. I will probably write
to you more about this after these Conferences.
Hope everything goes well with you and yours,
Sincerely,
J. D. Bernal
