More and more I'm wondering if before the RNA world there might have been a purine world - A and G.
Those bases are the most common in Miller type experiments.
Purines don't get dimers like pyrimidines - therefore I would think they would be safe under the UV
onslaught.
A RNA strand need not h-bond with complimentary bases. It could be all G, A, and assorted other
bases (I,U,C etc, in small amounts). When jumbled into a pile there would certainly be some h-
bonding among the bases.
And now to the interesting part. Let's say the strand is folded with two naked ends sticking out. If
those 2 ends are A or G, then it is likely we might have this type of coding: GA_, or GG_ Note the
center base is the key one and the rest are the more stable G with 3 h-bonds.
Also note that the N or _ base is wobble position. It may well have been that base farthest from the
folded part of the strand - and the most shakey.
GG_ is glycine - and with glycine we have no chirality problem. It is non polar
GA_ is glatamic acid or aspartic acid - both acidic.
Later GU_ would bring in basic aa's. Note there is no C needed yet.
Now IF, and chemists help me if you can, IF that loose end middle base could h-bond to the carboxyl
end of a peptide bond, I think we might have something here.
A purine world that connects an RNA strand's loose ends with peptide bonds.
I used to think the nucleotides helped stabilize the aa's. Now I think it is the other way around
and the aa's were key in stabilizing nucleotides.
Comment on any of this speculative idea?
Tom