29 March 1953
Dr. Max F. Perutz
Dear Dr. Perutz:
I am writing to try and clear up a situation that may have caused you some concern.
Word has reached me that you felt that I had obtained the idea of coiling helixes, in α keratin, from Crick, and had not acknowledged
my indebtedness to him.
I do not believe that you were in Cambridge when I visited there last summer. I had a long session with Crick, Kendrew, and
Huxley. There was only brief discussion of α keratin at this time, and, if my memory is correct, only a few sentences were
said about the coiled coil, as Crick calls it.
We discussed the fact that the 5.14-A meridional reflection offered some difficulties of explanation, and that also there
seemed to be a discrepancy in the density of α keratin. The discussion was very brief. Then Mr. Crick asked me if I had
ever thought of the possibility that the α helixes were twisted about one another. I answered that I had. So far as I can
remember, nothing more was said on this point.
I did not say anything more on the point because, although I knew that the simple idea of a coiled coil could account, at
least roughly, for the presence of the 5.15-A meridional reflection, I did not understand as yet how it accounted for the
density, and I was not sure that the explanation of the meridional reflection was completely satisfactory. I assume that
Crick said no more about the matter for essentially the same reason. Astbury and MacArthur later asked me if I knew how to
account for these troublesome features, and I said that I thought that I did, but was not yet sure. I felt reasonably sure
only after having completed some calculations of intensities, and having formulated the fundamental idea about the automatic
conversion of a straight helix into a compound helix through a repeating sequence of amino acid residues.
To summarize: I think that the only information about the coiled coil that I obtained from Crick was contained in his question
of me, when he asked if I had ever considered twisting the α helixes in α keratin. The idea was not a new one to me then,
but it had not yet been well worked out, and it seems to me that the way in which we worked it out, as described in our paper
in NATURE, is much different from that discussed by Crick. I hope that if my memory about the discussion in Cambridge is
at fault Mr. Crick will let me know.
If you have any further comments to make on this matter, I should be glad to learn about them.
I am hoping to see you when I make a brief visit in Cambridge in a few days.
cc: Dr. Crick