Figure 1

Common profile 1 for genomic trinucleotide frequencies and the average profile of its corresponding random sequences. Common profile 1 (black line) was obtained as the average of similar trinucleotide frequency profiles of 184 prokaryotic genomes (chromosomes) with GC content ranging from 16.56% to 42.83%. Alongside common profile 1 is the average trinucleotide frequency profile (green line) of 140 random sequences with GC content of 16%–43% and generated according to first-order symmetry. Trinucleotides in abscissa should be read vertically from bottom to top.