[ Eq(Derivative(x1, t), (-1)*k5*x1/k6),
  Eq(Derivative(x2, t), ((-1)*k7*x1*x2**k8/(k9**k8 + x2**k8) + 1*x21*k15*x3**k16/(k17**k16 + x3**k16) + (-1)*x9*k18*x2**k19/(k20**k19 + x2**k19))/k6),
  Eq(Derivative(x3, t), (1*k7*x1*x2**k8/(k9**k8 + x2**k8) + (-1)*x21*k15*x3**k16/(k17**k16 + x3**k16) + 1*x9*k18*x2**k19/(k20**k19 + x2**k19))/k6),
  Eq(Derivative(x4, t), ((-1)*x5*k37*x4**k38/(k39 + x4**k38) + 1*x12*k43*x16**k44/(k45**k44 + x16**k44) + 1*x19*k52*x16**k53/(k54**k53 + x16**k53))/k6),
  Eq(Derivative(x5, t), (1*x3*k10*x15**k11/(k12**k11 + x15**k11) + (-1)*x18*k46*x5**k47/(k48**k47 + x5**k47))/k6),
  Eq(Derivative(x6, t), (1*x16*k40*x17**k41/(k42**k41 + x17**k41) + (-1)*x14*k49*x6**k50/(k51**k50 + x6**k50))/k6),
  Eq(Derivative(x7, t), ((-1)*x6*k13*x7/(k14 + x7) + 1*x14*k31*x8**k32/(k33**k32 + x8**k32))/k6),
  Eq(Derivative(x8, t), (1*x6*k13*x7/(k14 + x7) + (-1)*x14*k31*x8**k32/(k33**k32 + x8**k32))/k6),
  Eq(Derivative(x9, t), (-1)*k1*x9/k6),
  Eq(Derivative(x10, t), ((-1)*x9*k21*x10**k22/(k23**k22 + x10**k22) + (-1)*x1*k24*x1*x10**k25/(k26**k25 + x10**k25) + (-1)*x5*k34*x10**k35/(k36**k35 + x10**k35) + 1*k2*x11)/k6),
  Eq(Derivative(x11, t), (1*x9*k21*x10**k22/(k23**k22 + x10**k22) + 1*x1*k24*x1*x10**k25/(k26**k25 + x10**k25) + 1*x5*k34*x10**k35/(k36**k35 + x10**k35) + (-1)*k2*x11)/k6),
  Eq(Derivative(x12, t), (1*x11*k27*x13**k28/(k29**k28 + x13**k28) + (-1)*k30*x12)/k6),
  Eq(Derivative(x13, t), ((-1)*x11*k27*x13**k28/(k29**k28 + x13**k28) + 1*k30*x12)/k6),
  Eq(Derivative(x14, t), 0/k6),
  Eq(Derivative(x15, t), ((-1)*x3*k10*x15**k11/(k12**k11 + x15**k11) + 1*x18*k46*x5**k47/(k48**k47 + x5**k47))/k6),
  Eq(Derivative(x16, t), (1*x5*k37*x4**k38/(k39 + x4**k38) + (-1)*x12*k43*x16**k44/(k45**k44 + x16**k44) + (-1)*x19*k52*x16**k53/(k54**k53 + x16**k53))/k6),
  Eq(Derivative(x17, t), ((-1)*x16*k40*x17**k41/(k42**k41 + x17**k41) + 1*x14*k49*x6**k50/(k51**k50 + x6**k50))/k6),
  Eq(Derivative(x18, t), 0/k6),
  Eq(Derivative(x19, t), 0/k6),
  Eq(Derivative(x20, t), ((-1)*x8*k3*x20/(k4 + x20) + 1*k55*x21)/k6),
  Eq(Derivative(x21, t), (1*x8*k3*x20/(k4 + x20) + (-1)*k55*x21)/k6) ]