1 April 1953
Dr. Daniel Mazia
Department of Zoology
University of California
Berkeley 4, California
Dear Dr. Mazia:
I am glad to have your letter of 11 March, and to know about your work on surface
films of deoxyribonucleic acid.
I am afraid that I do not have much to say about your first question - as to how to
account for the stability of DNA film over a solution in which the substance is soluble.
I agree with you that your measurement of 22 A for the thickness of the film agrees
nicely with our results. The diameter of our helix is about 18 A. If these molecules
were to be packed together in a surface film, there is a chance that the contact distance
would be somewhat less with a corresponding increase in the thickness of the film,
accordingly your value of 22 is, I think, compatible with our structure.
As to your third question, I do not have a strong feeling about the matter. I have
not thought enough about this matter as yet, to have formed a sound opinion.
It seems to me that the work that you and Mr. James have done adds one more piece
of evidence to support our structure, to the extent that it makes the thickness of
the molecule roughly 20 A.
I hope that you will continue to carry on work in this field. Professor Corey and
I do not feel at all sure that our structure is the correct one, but we do feel that
it will be possible, in the course of a few years, to determine the fundamental folding
of polynucleotide chains in the nucleic acids.