On the Origin of Protein Synthesis

Date:
1970-1976
Reference:
PP/CRI/H/6/1
Catalogue details

Licence: In copyright

Credit: On the Origin of Protein Synthesis. Source: Wellcome Collection.

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    the triplet part of the snticodon loop being underlined. Written out in full this becomes, for the mRNA, A A U A A U A A U A ^ * GGC GGC GGC U U A ¿Uul where ^ represents A or G, Jltc. Cj The base pairs allowed are always either A = U, G E C or G = U or their reversals. The pair A - C is not allowed, nor are A = G and G - G (see Crick, 196 ). Notice two points: (1) this restricted base sequence although written with commas for convenience of illustration, is comma-free (in the sense of Crick, fojLV LÎ , & Griffith, and Orgel, 195 jL tRNA with any of the possible loops specified above cannot go onto such a message in either of the two Hot/ Ux>ß incorrect phases and make five base pairs whether j^is in the FH or the hf configuration. The advantage, at this Btage of the problem, in having a comma-free code is not just that the message cannot then be read in the two incorrect phases (which would only improve efficiency by a factor of three) but that a tRNA cannot go onto the message, out .¿¿ttcr & l &> pi**™- of phase, just ahead of the growing point and^block the whole process^ . (2) the codons allowed are those found in the present code in the bot tom right-hand corner (as the codon table is usually written) and stand for GG c GA o AG c AA c I gly asp ser asn so that, for example, the anticodon loop for the glycine tRNA would be (35) UG GCG UU