Table 6. Classification of the 20 amino acids in the GKSAAP encoding scheme according to six different types of physicochemical properties.

Physicochemical property	Low	Middle	High
Accessible surface area	ACGILFV	HMPSTWY	RNDQEK
Side-chain orientation	NDQEK	ARGHPSTWYV	CILMF
Charge	DE	NQCILMFSWTYVAGP	KHR
Hydrogen-bond donors	ADCGST	NQEHILMPV	RKFWY
Hydrophobicity	THGSQ	RKNDEP	FIWLVMYCA
van der Waals potential	ILMFWY	RCQEHKPV	ANDGST