Here the blackened area represents the portion of charged residues E, D, K and R in a helix. This area increases from mesophiles to thermophiles. On the contrary, the amounts of amine residues, N and Q decrease in thermophilic helices. Also note that among hydrophobic groups (AILV) there is an increase in the contents of L and V. Each column shows the total content of any amino acid for all 12 genomes; thus the totals add up to 100%.