x1 = EI
x2 = PyrPI
x3 = EIP
x4 = HPr
x5 = EIPHPr
x6 = HPrP
x7 = EIIA
x8 = HPrPIIA
x9 = EIIAP
x10 = EIICB
x11 = EIIAPIICB
x12 = EIICBP
x13 = EIICBPGlc
x14 = PEP
x15 = Pyr
x16 = GlcP
x17 = Glc