Dioxygen binding thermodynamics

A thorough kinetic and thermodynamic analysis of this model system (small positive or negative enthalpies of formation are canceled by more negative entropies of formation) led Karlin s group to conclude that the stability of dioxygen binding is driven by favorable enthalpies, but unfavorable reaction entropies preclude observation of Cu2-02 at room temperatures.412... 

Despite differences in the chemical nature of the active sites, three classes of natural oxygen carriers display amazing similarities in thermodynamic and kinetic parameters that characterize dioxygen binding. All noncooperative proteins or isolated subunits of oligomeric oxygen carriers show reversible 1 1 02 binding (Equation 4.5). 

Steric effects also play a role in thermodynamics and kinetics of dioxygen binding to Vaska-type complexes. For example, ort/zo-substituents on arylphosphine ligands significantly decrease the oxygenation rate or even completely shut down the... 

Kinetic and thermodynamic data for dioxygen binding and release from a variety of hemoglobins are summarized in Table Notice that for... 

In tetraazamacrocyclic Co(II) complexes, the formation of /<-peroxo-Co(III) complexes following coordination of O2 to Co(II) complexes can be suppressed if the macrocycle is functionalized to inhibit face-to-face approach of the Co(II) centers. The thermodynamic stabilities of complexes [(X)LCo] (X =SCN or Q", L = C-meso-5,7,7,12,14,14-hexamethyl-l,4,8,ll-tetraaza-cyclotetradecane) have been determined and the effects of the anion X on the rate of dioxygen binding have been studied by laser flash photolysis after the flash, there is an immediate bleaching of the solution at the absorbance wavelength of the complex, followed by a slower return of absorbance. Reestablishment of the equilibrium for SCN can be analyzed in terms of Eq. (4) to (6) an analogous sequence applies when the anion is Cl . 

Thermodynamics of oxygen binding in natural and synthetic dioxygen complexes. E. C. Nieder-hoffer, J. H. Timmons and A. E. Martell, Chem. Rev., 1984, 84,137-203 (599). 

The thermodynamic association (or dissociation) constants used in the Adair equation for a ligand binding at sites in a multisite protein. The term Adair constants originally referred only to the four constants for the reversible binding of dioxygen to hemoglobin. See Adair Equation... 

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