an aromatic amino acid selected from the class consisting of anthranilic acid, p aminobenzoic acid, m aminobenzoic acid, 3 amino p toluic acid, {HEAD ~ 3 aminosalicylic acid}, 3 amino 4 methoxybenzoic acid, 6 amino m toluic acid, 3 amino 4 chlorobenzoic acid, {TAIL ~ 2 amino} 5 nitrobenzoic acid, 2 nitro 5 aminobenzoic acid, 5 aminoisophthalic acid 
an aromatic amino acid selected from the class consisting of anthranilic acid , p aminobenzoic acid , m aminobenzoic acid , 3 amino p toluic acid , { HEAD ~ 3 aminosalicylic acid } , 3 amino 4 methoxybenzoic acid , 6 amino m toluic acid , 3 amino 4 chlorobenzoic acid , { TAIL ~ 2 amino } 5 nitrobenzoic acid , 2 nitro 5 aminobenzoic acid , 5 aminoisophthalic acid
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH