{ diff(x1, t) = (1*k16*k1*x1*(1 - (x1 + x2)/k2) + (-1)*k16*k3*x5*x1/(k5 + x1) + (-1)*k16*k4*x1*x4/(k6 + x4))/k16,
  diff(x2, t) = (1*k16*k3*x5*x1/(k5 + x1) + (-1)*k16*k8*x2 + (-1)*k16*k4*x2*x4/(k6 + x4))/k16,
  diff(x3, t) = 1*k16*k9*x5*x3*(1 - x3/k10)/(k7 + x5)/k16,
  diff(x4, t) = (1*k16*k11*x3*(x1 + x5)/(x1 + x5 + k7) + (-1)*k16*k12*x4 + (-1)*k16*k13*x1*x4)/k16,
  diff(x5, t) = (1*k16*k8*k15*x2 + (-1)*k16*k14*x5)/k16 }