FIG. 1.

Average Lys (K) and Arg (R) residue contents in groups of AMPs. Each of the peptide groups (antiviral, antifungal, anticancer, and antibacterial peptides and peptides toxic to mammalian cells) was obtained by searching the APD (http://aps.unmc.edu/AP/main.html). Groups: 1, 80 antiviral peptides; 2, 405 antifungal peptides; 3, 82 anticancer peptides; 4, 1,035 antibacterial peptides; 5, 157 peptides that are toxic to mammalian cells; and 6, all 1,405 peptides analyzed. The average amino acid contents in each group were obtained by initiating the statistical analysis program at the end of the peptide output. Detailed data for the original 525 peptides were reported in our database paper (20).