Upon his return to the United States in the summer of 1953 Watson took up the study of RNA (ribonucleic acid), which as the
single-stranded companion molecule to DNA and the intermediary in protein synthesis held obvious interest for him and Crick.
Watson's studies resulted in the hypothesis that DNA made RNA, and that RNA made proteins.
Watson mentioned the difficulties he was facing in his "current attempt to make protein on N.A. [nucleic acid] surfaces"
(p.2), an attempt made in response to George Gamow's idea, later proved incorrect, that DNA could provide a direct, physical
template for the twenty amino acids that form the polypeptide chains of which proteins are made up. Despite these difficulties,
Watson stated that "[n]evertheless we persist and think we shall find a code" (p.2) for protein synthesis.
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1954-11-22 (November 22, 1954)
Watson, James D.
Original Repository: Wellcome Library for the History and Understanding of Medicine. Francis Harry Compton Crick Papers
I have meant to write for several weeks but I haven't had the time to write a long letter. Tonight I am also pressed and
so this must be short.
Our scheme concerning RNA. They remain much as before expect that we find any alternative scheme involving [diagrams] is just
as plausible as our original one. It gives an opposite prediction for the RNA base ratios (high GC -- low AT) and in fact,
this is observed. However in view of possible complications like RNA self replication at differential rates, I'm hesitant
to decide between alternatives. Also RNA
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chains with triply esterfied PO4 are tight though buildable [sic]. While Corey accepts contacts, better than in some previously
proposed structures, I really don't feel happy about them. Hence RNA may leave DNA template, as soon as chemical linkages
are formed. If this is true, all the monomers must be crystallized on DNA surface before joining up. This can be done with
hydrogen bonds between PO4's and sugar hydroxyls, energy coming either from ADP like source or from cyclic anhydride bonds.
We continue to like anhydrides as precursors.
All of this was good practice for our current attempt to make proteins on N.A. surfaces. A horrible task from every viewpoint.
Nevertheless we persist and think we shall find a code, though we doubt that this shall be correct one. Am back at Gamow idea
of DNA-protein. It would be rediculous [sic] to miss this because of prejudice for
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RNA. Am going under assumption that all (or almost all) sequences are possible. 39 steps in Cortieotropin, support this prosaic
Space filling models are essential even though troublesome and forever falling over and apart. We have almost all of Coreys
[sic] set but this is still not enough. Cambridge must acquire set if it is to enter code game. Need approximately 2000 atoms
(about 3000 dollars) This is not much money at current rates. I shall write to Max about this. I cannot really arrange deal
since it would smell of my returning to Cambridge. Hence Cambridge muse "enthuse" spontaneously
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Crellin has almost put R. Anode into use and so they cannot easily turn down request. Should be done soon or Alex Rich will
seize upon idea of having his set made by Caltech and then Cambridge will wait for years.
I am going to Berkeley over Thanksgiving and to East Coast over Christmas. Will try to be in Cambridge by summer. RNATIECLUB
has sponser [sic] -- Quartermaster Corps -- U.S. Army. Will pay for biannual meetings in Boston. We shall try to have you
invited for spring meeting.
What is Maurice doing.
regards to Odile
Please send me some P.R.S. reprints. Can I have 100. Many requests.