x1 = sul_ex
x2 = eth_ex
x3 = oxy_ex
x4 = oxy
x5 = H2O
x6 = A3c
x7 = aps
x8 = PPi
x9 = pap
x10 = sul
x11 = eth
x12 = A2c
x13 = hyd
x14 = cys
x15 = N2
x16 = N1
x17 = aco
x18 = oah
x19 = S1
x20 = S2
x21 = C1
x22 = C2
x23 = A2m
x24 = A3m
x25 = Ho
x26 = Hm