A new method for the determination of equilibrium constants through binding capacity measurements

The recent discovery of the negligible contribution of the triply ligated species to the oxygenation process of human hemoglobin A0 (S.J. Gill, E. Di Cera, M.L. Doyle, G.A. Bishop and C.H. Robert, Biochemistry 26 (1987) 3995) has pointed out the high precision of differential binding measurements. These measurements closely approximate the binding capacity (E. Di Cera, S.J. Gill and J. Wyman, Proc. Natl. Acad. Sci. U.S.A. 85 (1988) 449) of the system and can be used to calculate higher derivatives of the binding curve. We develop here a new method for the determination of equilibrium constants through binding capacity measurements by which the physical parameters expressing the optical properties of the system are eliminated in the data analysis.