December 9, 1953
Mr. George Gamow
19 Thoreau Drive
I have been interested to see your letter which arrived in Pasadena just about when I was leaving, on a trip to Israel.
The problem of the determination of sequence of amino-acid residues in the protein molecule through complementariness to the
nucleic acid molecule is a very interesting one, Corey and I thought about it in connection with our proposed structure
for nucleic acid (Proc. Hat. Acad. Sci. Feb., 1953) which stimulated Watson and Crick, who had a copy of the manuscript, to
develop their structure, and I know that Watson and Crick have thought it over too. I feel that a decision has to be made
through the consideration of the shapes of the molecules as to where the amino-acid residues fit in. The number of possibilities
is, as you point out, about enough to explain the selection uniquely of the residues, in position of about 3.5 Angstrom from
one another along the polynucleotide molecule.
The comment I would make about your number 20 is that I do not see the 12 that you rule out on the basis that they are D forms.
The rhomb is on one side of the nucleic acid molecule, and there is a polar axis along the molecule if a polypeptide chain
is being built up because the polypeptide chain itself has a polar axis. Hence, all 32 rhombs are to be considered as different.
In fact, I think that the number should still be multiplied by two.