Table 5.

Properties of amino acids used in their clusterization.

Property Name	Amino Acid Scale
Size	Size [52]
Size	Molecular weight [53]
Size	Residue volume [54]
Size	Bulkiness [55]
Hydrophobicity	Normalized hydrophobicity scales for $\alpha$-proteins [56]
Hydrophobicity	Consensus normalized hydrophobicity scale [57]
Hydrophobicity	Hydropathy index [58]
Hydrophobicity	Surrounding hydrophobicity in $\alpha$-helix [59]
Polarity	Polarity [60]
Polarity	Mean polarity [61]
Occurrence in $\alpha$-helices	Signal sequence helical potential [62]
Occurrence in $\alpha$-helices	Normalized frequency of N-terminal helix [63]
Occurrence in $\alpha$-helices	Relative frequency in $\alpha$-helix [64]