[Discussion transcription]

Date:
[c. 1956]
Reference:
PP/CRI/H/2/15
Catalogue details

Licence: In copyright

Credit: [Discussion transcription]. Source: Wellcome Collection.

    1/48
    I â SESSION V-A (Chargaff) DR. MATTHEWS: As Dr. Chargaff has pointed out, we have no information at present I about the sequence of nucleotides in RNA and DNA. Under these conditions speculation can run riot, and in certain quarters it has in the last year or two - in particular, the idea that a triplet of nucleotides (3 of the h) might be responsible for the position of one amino acid. We can't do anything in the way of sequence to test this hypothesis, but we can look at composition in extreme casos. We have already known a case of this plant virus turnip yellow mosaic, which has 37% cytidylic acid in its RNA. The protein has recently been analyzed, and it contains, as the highest constituent, 10% serine and it's a perfectly ordinary protein. Looking for another extreme case, we thought' of the silk gland in the silk moth, which as you recall produces a protein with about ix% or £0$ glycine. If it's anything like this at work, we mi$it expect a rather odd ribonucleic acid. Very simply, we took the silk gland and the gut. The gut is a general tissue with many cell types. The silk gland, very rich in nucleic acid, produces these peculiar proteins and practically nothing else, but its RNA has a composition which one can hardly distinguish from the generalized RNA of the gut. This proves or disproves nothing, but it's not quite what one would expect from the triplet idea. DR. McELROYî Have there been other comparisons made with an end group analysis to the molecular weight determined by other methods? DR. SEYMOUR COHEN; The only comparison that has been made is in the turnip yellow 0 system, in which Drs. Smith and Markham obtained a value of 1$,000 to 17,000 and we have obtained an average value of about twice that. Now, there is a point that I would like to bring up about the very interesting recent results of Dr. Warner and Dr. Ochoa where they obtained a pairing of polyadenine nucleotides and polyuradine nucleotides. This also fits in with the apparent pairing which Dr. Chargaff's analysis seems to point to of the various bases 6 amino-6 hydroxyl. Although Dr. Crick objected, one would like to know whether this is at all possible. In other words, what we have seen is actually an aggregation, and what Dr. Stoith has observed in turnip yellow arc the actual