Summary: My suggestion is that the proto-tRNA first joined to aa's through one base pair from the
acceptor stem. And that this base pair attached to the aa side opposite the side chain (R) which is
HHO, HHO, HHO etc. (I'm looking at chem charts of peptide bonds)
The G or C base with 3 hydrogen bonds, attached to HHO, The A or U base with 2 hydrogen bonds,
attached to _HO
This suggests reasons for the connection between AA's and codon/anticodon, why D over L, and how the
first peptide bond may have been lined up - maybe.
Let's pretend that the proto-tRNA joined to the amino acids (AA) through a base pair on the acceptor
stem. Where would it join? How would it work? I don't know chemistry so this is mostly guess work
but here goes (Corrections welcomed)
If the proto - tRNA joined to the aa through a base pair then the side chain would not be important
at first. I think I can show why.
The proto-tRNA would join - not to the side chain of the AA, as I first thought - but instead to the
opposite side that has an h. This would be the same on all aa's. When a peptide bond forms you can
see that this side has the configuration of HHO, HHO, HHO.
Could this be the way a proto-tRNA links up with the aa with one base. If the base was an A or U it
would join up with _HO (of the HHO) If the base was a G or C it would join up with HHO.
OR A single base from the adaptor stem would connect to HHO on the AA with:
two hydrogen bonds if the base was either A or U in the proto-tRNA. _HO And this bond would denature
or split apart at the same time that an A or U bond in the codon/anticodon (co/aco) would denature.
3 hydrogen bonds if the base was either G or C in the proto-tRNA. HHO And this bond would denature
or split apart at the same time that an G or C bond in the co/aco would denature.
This would solve the D and L amino problem
Any aa connected by any base would denature or split apart when the hydrogen bonds were broken. But
because we now have 2 groups the A or U with a 2 h bonded base connected to AA's or the G or C with
a 3 bonded base connected to AA's There would be two groups of aa's:
First group of A or U base, would more quickly denature in raising temp. 2nd group of G or C base,
would more slowly denature in raising temp.
First group would separate in cooler and wette? environment than the 2nd group.
Though all AA's would bond at similar point, (the side opposite the R side) they would soon be
selected for their environment. And gradually settle into two groups.
Ex. 1 The G or C base that is bonded to AA's (at HHO, HHO, etc.) breaks or denatures at the same
time that a G or C breaks in the co/aco position
Thus GC in the co/aco will release at the same time that the G or C base that is hydrogen bonded to
the aa releases.
Ex. 2. The A or U base that is bonded to AA's (at (H)HO) breaks or denatures at the same time that a
A or U breaks in the co/aco position
Thus AU in the co/aco will release at the same time that the A or U base that is hydrogen bonded to
the aa releases.
This also suggests how peptide bonds could have evolved in that the proto-tRNAs would line up on the
opposite side of the side chain on the HHO, side.
Comment? Tom