Fig 3.03

Fig 3.03#

Michaelis-Menten kinetics

using OrdinaryDiffEq
using ModelingToolkit
using Catalyst
using Plots
Plots.default(linewidth=2)

Reaction network

rn = @reaction_network begin
    (k1, km1), S + E <--> ES
    k2, ES --> E + P
end

\[\begin{split} \begin{align*} \mathrm{S} + \mathrm{E} &\xrightleftharpoons[\mathtt{km1}]{\mathtt{k1}} \mathrm{\mathtt{ES}} \\ \mathrm{\mathtt{ES}} &\xrightarrow{\mathtt{k2}} \mathrm{E} + \mathrm{P} \end{align*} \end{split}\]

setdefaults!(rn, [
    :S=>5.,
    :ES=>0.,
    :E=>1.,
    :P=>0.,
    :k1 => 30.,
    :km1 => 1.,
    :k2 => 10.,
])

osys = convert(ODESystem, rn; remove_conserved = true) |> structural_simplify

\[\begin{split} \begin{align} \frac{\mathrm{d} E\left( t \right)}{\mathrm{d}t} &= \mathtt{k2} \left( - E\left( t \right) + \Gamma_{1} \right) + \mathtt{km1} \left( - E\left( t \right) + \Gamma_{1} \right) - \mathtt{k1} E\left( t \right) S\left( t \right) \\ \frac{\mathrm{d} S\left( t \right)}{\mathrm{d}t} &= \mathtt{km1} \left( - E\left( t \right) + \Gamma_{1} \right) - \mathtt{k1} E\left( t \right) S\left( t \right) \end{align} \end{split}\]

observed(osys)

\[\begin{split} \begin{align} \mathtt{ES}\left( t \right) &= - E\left( t \right) + \Gamma_{1} \\ P\left( t \right) &= E\left( t \right) - S\left( t \right) + \Gamma_{2} \end{align} \end{split}\]

tend = 1.0

1.0

prob = ODEProblem(osys, [], tend)
sol = solve(prob)

retcode: Success
Interpolation: 3rd order Hermite
t: 37-element Vector{Float64}:
 0.0
 0.006600703726699514
 0.01022277056012863
 0.015543467478140675
 0.02051947168533509
 0.02641018786018821
 0.03261917715421904
 0.03974230175678756
 0.04773168899544981
 0.0570841908779507
 ⋮
 0.6470324023587559
 0.6931031408477125
 0.7367683827322631
 0.7791059865493958
 0.8212466198548
 0.8642333668324144
 0.9090993660547448
 0.9568878660418696
 1.0
u: 37-element Vector{Vector{Float64}}:
 [1.0, 5.0]
 [0.4180476197959369, 4.395302952712939]
 [0.28277703335226406, 4.2362793319463865]
 [0.1791117446616879, 4.091342551218704]
 [0.13285191002575414, 4.002950476488607]
 [0.10715692365888231, 3.9253138062440045]
 [0.09568932433965065, 3.8580005265583313]
 [0.09092109954691632, 3.788614104823389]
 [0.0898206023516353, 3.7148221391871403]
 [0.09058864991025081, 3.6304918096088135]
 ⋮
 [0.7252277328768328, 0.04840338534337177]
 [0.8069728851541074, 0.02310068905541521]
 [0.866384281219644, 0.011833488316888211]
 [0.9083028367930726, 0.006550597043571017]
 [0.9376852665106246, 0.0038559086789705377]
 [0.9582641290934262, 0.002355825567417385]
 [0.9726435047202581, 0.0014581179992702214]
 [0.9825982936657854, 0.0008953036977517524]
 [0.9884434120994311, 0.0005834282632163945]

@unpack S, ES, E, P = osys
plot(sol, idxs=[S, ES, E, P], xlabel="Time (AU)", ylabel="Concentration (AU)", legend=:right, title="Fig 3.03")

../_images/fa40391e303e8a0f8f60d186ac70ed888b0177ca40a2c5492c1dbe306ff0ef95.png

rn303mm = @reaction_network begin
    mm(S, k2 * ET, (km1 + k2) / k1), S ⇒ P ## using \Rightarrow
end

\[ \begin{align*} \mathrm{S} &\xrightarrow{\frac{\mathtt{ET} S \mathtt{k2}}{S + \frac{\mathtt{k2} + \mathtt{km1}}{\mathtt{k1}}}} \mathrm{P} \end{align*} \]

setdefaults!(rn303mm, [
    :S=>5.,
    :ET=>1.,
    :P=>0.,
    :k1 => 30.,
    :km1 => 1.,
    :k2 => 10.,
])

osysmm = convert(ODESystem, rn303mm; remove_conserved = true) |> structural_simplify

\[ \begin{align} \frac{\mathrm{d} S\left( t \right)}{\mathrm{d}t} &= \frac{ - \mathtt{ET} \mathtt{k2} S\left( t \right)}{\frac{\mathtt{k2} + \mathtt{km1}}{\mathtt{k1}} + S\left( t \right)} \end{align} \]

tend = 1.0
probmm = ODEProblem(osysmm, [], tend)
solmm = solve(probmm)

retcode: Success
Interpolation: 3rd order Hermite
t: 15-element Vector{Float64}:
 0.0
 0.08829951015219592
 0.2967725537625472
 0.5000004875811703
 0.6196473972837556
 0.6670104453577671
 0.7099275100893456
 0.7465737578395125
 0.7827003202641042
 0.8170029171212273
 0.8515324938674043
 0.8866728375768105
 0.9240249128338719
 0.9646817216791721
 1.0
u: 15-element Vector{Vector{Float64}}:
 [5.0]
 [4.182468228248958]
 [2.3146741114200724]
 [0.7140966653045732]
 [0.13296502509373836]
 [0.04630250749684772]
 [0.01563176034250213]
 [0.005910624536905458]
 [0.0022299117086426626]
 [0.0008784935038914966]
 [0.00034320139778785724]
 [0.00013175527102757075]
 [4.761595514034663e-5]
 [1.5733007241346686e-5]
 [6.0074984467007344e-6]

@unpack S, P = osys
fig = plot(sol, idxs=[S, P], line=(:dash), label=["S (full)" "P (full)"])
plot!(fig, solmm, idxs=[S, P], label=["S (MM)" "P (MM)"])
plot!(fig, title="Fig. 3.03",
    xlabel="Time (AU)", ylabel="Concentration (AU)",
    xlims=(0., tend), ylims=(0., 5.), legend=:right
)

../_images/9a704fb0851ac652f434bf2029337963f57bbd6efdb229b8710c9c3201ba690c.png

This notebook was generated using Literate.jl.