Biochemistry Example
Binding of O2 to Hemoglobin


This example is due to Prof. R. A. Alberty of M.I.T. (private communication), and is based on earlier work of Ackers and Halvorson ( Proc. National Academy of Sci. USA, 71, 4312 (1974)). It involves the binding of oxygen to hemoglobin in human blood, an important biochemical system.

In solution, there exist dimers and trimers of heme, and these form complexes with O2, resulting in the eight species, D(O2)2, DO2, D, T, TO2, T(O2)2, T(O2)3, T(O2)4, where D represents the dimer and T represents the trimer.

Using data for the seven dimer and trimer binding constants, Alberty calculates the equilibrium species distribution as a function of the concentration of O2 and the initial amount of heme. Fixing the concentration of O2 as a problem parameter is an example of an Equilibrium Constraint. This problem also illustrates the use of Reaction Input Data.

An example of such a problem is included in all versions of EQS4WIN. There exist many similar related biochemistry problems. A recent discussion of a class of these is contained in the paper Computer-modelling of metal speciation in human blood serum, P. Letkeman, Journal of Chemical Education, 2, (1996).

Hemoglobin Binding
Click on image to enlarge (17.8K)