Figure 1

Free folding energies in different codon residues. Free folding energies (FFE) were determined in phase-selected subsequences of 81 different genes. The original nucleic acids contained the intact three-letter codons (1^st+2^nd+3^rd). Subsequences were constructed by periodic removal of one letter from the codon and maintaining the other two (1^st+2^nd, 1^st+3^rd, 2^nd+3^rd) or removing two letters and maintaining only one (1^st, 2^nd, 3^rd). Distinction was made between exons (B and D) and the preceding (-1, A) and following (+1, C) sequences (introns). The dG values were determined by mfold and the FFE was calculated. Each bar represents the mean ± SEM, n = 81.