{ diff(x1, t) = ((-1)*k39*k1*x1/(k2 + x1) + 1*k39*k3*x2/(k4 + x2))/k39,
  diff(x2, t) = (1*k39*k1*x1/(k2 + x1) + (-1)*k39*k3*x2/(k4 + x2))/k39,
  diff(x3, t) = ((-1)*k39*k5*x3*x2/(k6 + x3) + 1*k39*k7*x4/(k8 + x4) + (-1)*k39*k33*x3*x9/(k34 + x3) + 1*k39*k35*x5/(k36 + x5))/k39,
  diff(x4, t) = (1*k39*k5*x3*x2/(k6 + x3) + (-1)*k39*k7*x4/(k8 + x4))/k39,
  diff(x5, t) = (1*k39*k33*x3*x9/(k34 + x3) + (-1)*k39*k35*x5/(k36 + x5))/k39,
  diff(x6, t) = ((-1)*k39*(k9*x4*x6/(k10 + x6) + k11*x11*x6/(k12 + x6)) + 1*k39*k13*x7/(k14 + x7))/k39,
  diff(x7, t) = (1*k39*(k9*x4*x6/(k10 + x6) + k11*x11*x6/(k12 + x6)) + (-1)*k39*k13*x7/(k14 + x7))/k39,
  diff(x8, t) = ((-1)*k39*k15*x8*x7/(k16 + x8) + 1*k39*k17*x9/(k18 + x9) + (-1)*k39*(k29*x8*x15 - k30*x13))/k39,
  diff(x9, t) = (1*k39*k15*x8*x7/(k16 + x8) + (-1)*k39*k17*x9/(k18 + x9))/k39,
  diff(x10, t) = ((-1)*k39*k19*x10*x2/(k20 + x10) + 1*k39*k21*x11/(k22 + x11) + (-1)*k39*(k31*x10*x15 - k32*x14))/k39,
  diff(x11, t) = (1*k39*k19*x10*x2/(k20 + x10) + (-1)*k39*k21*x11/(k22 + x11))/k39,
  diff(x12, t) = 0/k39,
  diff(x13, t) = 1*k39*(k29*x8*x15 - k30*x13)/k39,
  diff(x14, t) = 1*k39*(k31*x10*x15 - k32*x14)/k39,
  diff(x15, t) = ((-1)*k39*(k23*x9*x15/(k24 + x16) + k25*x11*x15/(k26 + x15)) + 1*k39*k27*x16/(k28 + x16) + (-1)*k39*(k29*x8*x15 - k30*x13) + (-1)*k39*(k31*x10*x15 - k32*x14) + 1*k39*k37)/k39,
  diff(x16, t) = (1*k39*(k23*x9*x15/(k24 + x16) + k25*x11*x15/(k26 + x15)) + (-1)*k39*k27*x16/(k28 + x16) + (-1)*k39*k38*x16)/k39 }