Table 1.

Classification of 20 amino acids into four bead types, L, N, V, and B

20	4	20	4	20	4	20	4
Trp	B	Met	V	Tyr	V	Asn	N
Val	B	Cys	V	Ser	N	Gln	N
Leu	B	Pro	V	Gly	N	Glu	L
Ile	B	Ala	V	His	N	Asp	L
Phe	B	Thr	V	Lys	N	Arg	L

The grouping is determined by minimizing Eq. 9.