From the evolutionary perspective, once there should be a time when proteins were synthesized in a fashion without adaptor i.e. tRNA [R. Balasubramanian, 1985]. And if so, still it would be possible to form polypeptides in the same manner inside a ‘Modern Cell’Is there any such ‘Ancient Protein’?
N.B. In order to harmonize with my question, here I have used the word 'Ancient' instead of 'Primitive' as was used in the reference .
Ref: R. Balasubramanian, “Conformational studies on nucleotide-amino acid interactions leading to origin of life”, Proc. Int. Symp. Biomol. Struct. Interactions, Suppl, J. Biosci., Vol. 8, Nos 3&4, August 1985, pp. 823-835. (Attached)
You can look up Non ribosomal peptide synthesis and ployketide synthesis for some clues. If my understanding is correct even fatty acid biosynthesis. They do not need adapters, but are quite large to assemble.
Oligopeptides such as some antibiotics and precursors to bacterial peptidoglycan are synthesized by non-ribosomal pathways, with a separate (ribosome-synthesized) enzyme for each step of the reaction. So far as I know, there are no "full-sized" proteins synthesized this way.
I think the prevailing hypothesis is that proteins came after RNA so there may have neevr been a machinery that synthesized full-sized proteins without tRNA. The remenants of RNA as functioning molecules are visible even today as nucleotides are cofactors of many enzymes.
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