A speculation on the origin of protein synthesis

@article{Crick2004ASO,
  title={A speculation on the origin of protein synthesis},
  author={Francis H. C. Crick and Sydney Brenner and Aaron Klug and George Pieczenik},
  journal={Origins of life},
  year={2004},
  volume={7},
  pages={389-397}
}
It is suggested that protein synthesis may have begun without even a primitive ribosome if the primitive tRNA could take up two configurations and could bind to the messenger RNA with five base-pairs instead of the present three. This idea would impose base sequence restriction on the early messages and on the early genetic code such that the first four amino acids coded were glycine, serine, aspartic acid and aspargine. A possible mechanism is suggested for the polymerization of the early… 
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Strong correlations in the enzyme family of Ile-, Phe-, Val-, Met-, and Leu-tRNA synthetases suggests that these enzymes evolved last, and that an earlier version of the Genetic Code was comprised solely of codons containing a central purine.
A conformational rationale for the origin of the mechanism of nucleicacid-directed protein synthesis of ‘living’ organisms
TLDR
The nucleicacid-directed protein synthesis is shown to be a natural consequence of a particular way of favourable interaction between nucleic acids and amino acids, and the model provides the missing link between the chemical evolution of small organic molecules and biological evolution through the process of mutations in nucleicacids and nucleic acid-directedprotein synthesis.
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