Franklin's relations with both Watson and Crick improved greatly once she moved from King's College to Birkbeck College,
and she was in regular contact with both as she worked on the structure of TMV. In this letter, Crick commented at length
on a manuscript Franklin had sent for review.
Number of Image Pages:
2 (105,966 Bytes)
1954-12-08 (December 8, 1954)
Original Repository: Churchill Archives Centre. The Papers of Rosalind Franklin
Many thanks for your letter and the draft paper. I had heard that Max had had a copy, but as I expect you know, he is away
sick, and so I haven't been able to discuss it with him.
A few comments occur to me. On page 4: the reason for meridional reflection being absent is strictly that the electron density
projected onto the axis is smooth. For the case you give, all the 3n + 1 and 3n + 2 layer lines would be weak, which is perhaps
true up to a point.
Experience in the past has shown that it is rash to include a drawing with speculation features. It turns up for years and
years, and ones reservations get lost in the process. I should be very cautious about your figure 3.
At the bottom of page 5: the real amplitudes of the equatorial reflections comes simply from the screw axis, and not of course,
because of any pseudo-symmetry. (This is just a matter of your wording.)
I think you should also be cautious about the X-ray value for the molecular weight of the sub-unit. How possible are values
of another than 12? The chemical values, on the face of them, seem rather good. While we are on this point, I am puzzled
about the molecular weight and hydration of TMV. Have you been over all the data carefully? What is wrong, for instance,
with Williams' argument in the Cold Spring Harbour Symposium, 1953, page 193?
I don't really like the bit on page 7 about the extra surface. The groove is, after all, not yet firmly established.
How much surface, in term of angstroms squared, does the chemical work suggest? If you find you can change the salt concentration
of the medium you may be able to get much better evidence for the groove.
Finally, have you considered that we have no particular reason that the layer-lines are regular, i.e. why the 3n + 1 and 3n
+ 2 are not staggered relative to the 3n ones, as they are, for example, in the alpha-helix. Do your layer-line measurements
show any sign of this? If not, how does one explain the fact that the helix repeats exactly after 3 turns?
I hope you won't mind all the criticism. Otherwise the paper is fine, though I was surprised you omitted the method by
which you obtained the signs of the equatorials. You don't say where you propose to publish the paper. I would have
thought B. et B. Acta. Practically everybody interested reads it nowadays.
Beatrice is still waiting to hear about her job.
Sydney was here for a few days. A great treat. We managed to cover a lot of ground.