ConstantAmount - Specify variable or constant species amount

Description

The ConstantAmount property indicates whether the quantity of the species object can vary during the simulation. ConstantAmount can be either true or false. If ConstantAmount is true, the quantity of the species cannot vary during the simulation. By default, ConstantAmount is false and the quantity of the species can vary during the simulation. If ConstantAmount is false, the quantity of the species can be determined by reactions and rules.

The property ConstantAmount is for species objects; the property ConstantValue is for parameter objects.

More Information

The following is an example of modeling species as constant amounts:

Modeling the role of nucleotides (GTP, ATP, cAMP) and cofactors (Ca⁺⁺, NAD⁺, coenzyme A). Consider the role of GTP in the activation of Ras by receptor tyrosine kinases.

Ras-GDP + GTP  -> Ras-GTP + GDP

Model GTP and GDP with constant amount set to true. In addition, you can set the BoundaryCondition of these species to true, thus making them boundary species.

Characteristics

Applies to	Object: species
Data type	boolean
Data values	true or false. The default value is false.
Access	Read/write

Examples

1. Create a model object named my_model.

   modelObj = sbiomodel ('my_model');

2. Add a species object and verify that the ConstantAmount property setting is 'false' or 0.

   speciesObj = addspecies (modelObj, 'glucose');
   get (speciesObj, 'ConstantAmount')

   MATLAB returns:

              ans =
   
        0

3. Set the constant amount to 'true' and verify.

   set (speciesObj, 'ConstantAmount', true);
   get (speciesObj, 'ConstantAmount')

   MATLAB returns:

   ans =
   
        1

See Also

addspecies, BoundaryCondition

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