X.3.3.3.2 Some physicochemical properties of amino acids are correlated with the properties of the triplets that encode them
From the viewpoint of discussion of the evolution of the genetic code, it could also be important that a correlation exists between certain properties of aminoacids and the corresponding triplets of the genetic code (Tolstrup et al. 1994).At random, we can, for example, mention the high positive correlation of the index of hydrophobicity of aminoacidsand the 3’-dinucleotides of the corresponding anti-codons, or the negative correlation of the chemical reactivityof aminoacids in the formation of peptide bonds and the content of nucleotides G andC in the corresponding codon.According to some authors, these correlations indicate that, at the beginning of the evolution of the genetic code, direct stereochemical interactions between the aminoacids and the corresponding codons and anticodons also participated in assigning of codons to the individual aminoacids (Woese 1965; Shimizu 1982).The original stereochemical hypothesis of the formation of the genetic code tends, however, to be gradually abandoned at the present time or has undergone substantial changes (Alberti 1999; Di Giulio 2001).