Transfer RNA and the translation apparatus in the origin of life

At present we have some understanding about the mechanisms of prebiotic synthesis and polymerization. Experiments are also being carried out on the prebiotic replication of the nucleic acids. However, the greatest gap in our knowledge is the prebiotic mechanism for the polynucleotide directed synthesis of polypeptides. Some insight into potential mechanisms of this type is afforded by the recent determination of the three-dimensional structure of yeast phenylalanine rRNA. The poly-nucleotide chain id found to be highly folded and the molecule is found in an L shaped configuration. One end of the L shaped molecule contains the anticodon loop; that arm of the L is made of the double helical anticodon and dihydro U stems. The other end of the L shaped molecule contains the 3'OH adenosine to which the amino acid is added during aminoacylation. That arm of the L is built of the double helical CCA and T?C stems. The corner of the L is formed by the close approximation of the T?C loop and dihydro U loop. The distance between the anticodon and the 3'OH adenosine end of the molecule is 76 Å. Comments are made about the manner in which the tRNA molecule may have evolved and in addition, some suggestions are presented about the prebiotic interactions of primitive tRNA polynucleotides and messenger RNA strands.