Table 1.

Number of possible peptide sequences encompassing the chemical space of peptides of a given length (n).

Peptide length (n)	Number of peptides in the chemical space (20n)	Chemical space limited to cationic (2) and hydrophobic (8) residues ((2+8)n)
2	400	100
3	8,000	1,000
4	160,000	10,000
5	3,200,000	100,000
6	64,000,000	1,000,000
7	1,280,000,000	10,000,000
8	25,600,000,000	100,000,000
9	512,000,000,000	1,000,000,000
10	10,240,000,000,000	10,000,000,000
20	1.05 × 1026	1 × 1020
30	1.07 × 1039	1 × 1030