The model contains one compartment called C. There are four species called S1, S2, S3 and S and three parameters called k1, k2 and k3. The model contains two reactions defined as:
Reaction | Rate |
S1 → S3 | k1 · S1 · C |
S3 → S1 | k2 · S3 · C |
Reaction S1 → S3 defines one local parameter k1 and reaction S3 → S2 defines one local parameter k2. These parameters have a scope local to the defining reaction and are different from the global parameters k1 and k2 used in the rules.
The model contains two rules:
Type | Variable | Formula |
Assignment | S4 | k3 · S1 |
Rate | S2 | k2 · S3−k1 · S1 |
Note that in this case the initial value of species S4 is not explicitly declared and must be calculated by the assignmentRule.
The initial conditions are as follows:
Value | Units | |
Initial amount of S1 | 1 × 10−5 | mole |
Initial amount of S2 | 1.5 × 10−5 | mole |
Initial amount of S3 | 1 × 10−5 | mole |
Initial amount of S4 | undeclared | mole |
Value of parameter k1 | 0.015 | second-1 |
Value of parameter k2 | 0.5 | second-1 |
Value of parameter k3 | 1.5 | dimensionless |
Value of local parameter k1 | 0.01 | second-1 |
Value of local parameter k2 | 0.4 | second-1 |
Volume of compartment C | 1 | litre |
The species values are given as amounts of substance to make it easier to use the model in a discrete stochastic simulator, but (as per usual SBML principles) their symbols represent their values in concentration units where they appear in expressions.