{ diff(x1, t) = (1*k27*k4*k1/(k2^(-1) + k1) + (-1)*k27*k3*x2*x1)/k27,
  diff(x2, t) = (1*k27*k5*(k1/(k6^(-1) + k1) + k7*x5) + (-1)*k27*k24*x6*x2)/k27,
  diff(x3, t) = (1*k27*k8*(k9 - x4 - x3)*x6/(k10 + k9 - x4 - x3 + x6) + (-1)*k27*k11*x3*x5)/k27,
  diff(x4, t) = (1*k27*k11*x3*x5 + (-1)*k27*k12*x4*x1/(k13 + x4 + x1) + (-1)*k27*k14*x4*x2/(k15 + x4 + x2))/k27,
  diff(x5, t) = ((-1)*k27*k11*x3*x5 + 1*k27*k12*x4*x1/(k13 + x4 + x1) + 1*k27*k14*x4*x2/(k15 + x4 + x2) + 1*k27*k16*(k1/(k17^(-1) + k1) + k25*x5) + (-1)*k27*k18*x6/(k19 + x6)*x5)/k27,
  diff(x6, t) = (1*k27*(k20*x2 + k21*x5 + k22*x6^2*x2) + (-1)*k27*k23*x6)/k27 }