In the fourth and final part of the book we develop MASS models that include macromolecular functions that are coupled with metabolites. Many proteins in cells bind to small molecules and the bound states of the proteins have different functions than the unbound forms.

The simplest and perhaps best known case is that of oxygen binding to hemoglobin. DPG23 is a unique metabolite in the red cell that binds to hemoglobin and alters the oxygen-carrying capacity of hemoglobin. DPG23 is made by a simple bypass on glycolysis, and in Chapter 13 we couple this bypass to the glycolytic model developed earlier in Chapter 10.

Furthermore, the kinases in glycolysis can bind to many metabolites. Some binding states inhibit enzyme catalysis and some activate function. In Chapter 14 we show how such regulatory models can be incorporated into the glycolytic model. With these examples, the reader should have the basic understanding of the procedure and data needs for building large-scale kinetic models in cell and molecular biology.