Letter from Rosalind Franklin to Donald L. D. Caspar
Biophysicist Donald Caspar had recently finished his doctoral work on TMV structure, and had contacted Franklin at James Watson's
suggestion. In this letter she commented on his thesis and other papers and discusses her recent work with heavy-atom substituted
TMV. Caspar worked with Franklin's team during the 1955-56 year, helping them determine the configuration of TMV.
Number of Image Pages:
1 (71,716 Bytes)
1955-06-28 (June 28, 1955)
Caspar, Donald L. D.
California Institute of Technology
Original Repository: Churchill Archives Centre. The Papers of Rosalind Franklin
Reproduced from the Franklin Collection at the Churchill Archives Centre with the permission of the copyright holder.
Very many thanks for your letter, thesis, and RNA paper, all of which I found extremely interesting. I am very impressed
by the accuracy of your low-angle measurements, and am quite happy about your choice of signs. The sign combination which
I mentioned in a letter to Jim was based on an over-simplification of the effect of the groove. This is all discussed in a
paper which I hope to be able to post at the end of this week.
I am sorry you have not yet had a copy of the paper I sent to Dr. Siegel. I had hoped to be able to send it with my last
letter, but there has been a long delay in getting it copied.
I have recently taken some high-resolution low-angle photographs of Schramm's A-protein. This shows a weak but definite
peak between the first two subsidiary maxima of TMV. This seems a rather satisfactory confirmation of your signs in this
I have also got good photographs of Fraenkel-Conrat's iodinated TMV. The change is not at all similar to that of your
Pb compound - which is, of course, consistent with the finding that the Pb does not go on to the S.
I look forward to being able to discuss all these things at length with you and Jim.