WOLFRAM|DEMONSTRATIONS PROJECT

Nonlinear Chemical Dynamics: The Peroxidase-Oxidase Reaction

​
length of simulation (time)
parameters
A
0
k
1
k
2
k
3
k
4
k
5
k
6
k
7
k
8
initial conditions
A(0)
B(0)
X(0)
Y(0)
The peroxidase-oxidase (or PO) reaction is an enzyme-catalyzed chemical reaction that has been extensively studied in horseradish plants. The overall reaction
2NADH+
O
2
+2
+
H
2
+
NAD
+2
H
2
O
can be modeled by a set of four first-order ODEs developed by Lars Olsen [2], which represent the reactants, products, and intermediates of the reaction. What makes this reaction so special is its nonlinear nature; with the right parameters, oscillatory behavior, period doubling, and chaos can be observed.
The equations in this Demonstration were taken directly from [1] and are as follows:
A'=
k
7
(
A
0
-A)-
k
3
ABY​​B'=
k
8
-
k
1
BX-
k
3
ABY​​X'=
k
1
BX-2
k
2
2
X
+3
k
3
ABY-
k
4
X+
k
6
​​Y'=2
k
2
2
X
-
k
5
Y-
k
3
ABY
Here
k
1
to
k
8
represent rate constants of the intermediate reactions;
A
,
B
,
X
, and
Y
represent
O
2
,
NADH
,
NAD+
, and
CoIII
, respectively, with their differentials representing their intermediates.
The suggested settings are
k
1
=0.35
,
k
2
=250
,
k
3
=0.035
,
k
4
=20
,
k
5
=5.35
,
k
6
=
-6
10
,
k
7
=0.1
,
k
8
=0.825
,
a
0
=8
,
A(0)=6
,
B(0)=58
,
X(0)=0
,
Y(0)=0
.