SimBiology®

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 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

Example

1. Create a model object with name 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 constant amount to 'true' and verify

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

   MATLAB returns

   ans =
   
        1

See Also

addspecies, BoundaryCondition

Composition

ConstantCapacity