Figure 5. Amino acid compositions of catalytic sites in anaerobic (in blue) and aerobic (in red) enzymes.

It can be seen that anaerobic enzymes use polar amino acid residues (e.g., Asp, Glu, Lys and Arg) in catalytic sites more frequently (P<0.05), while aerobic enzymes use non-polar residues (e.g., Trp and Ile) more often (P<0.05).