Dioxygen binding kinetics

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... 

ESR-silent, suggesting low-spin Fe11. This has been confirmed by the use of Mossbauer spectroscopy. Kinetic studies suggest that a substrate-enzyme complex is formed before interaction with dioxygen. Binding of substrate has no effect upon the Mossbauer spectrum, so it is not certain that it binds to the Fe11 centre. 

Rate and equilibrium constants for O2 and CO binding to Fe hemes have been measured in various solvents and at various temperatures. Dioxygen binding to Fe porphyrins can be studied at low temperatures by a variety of spectroscopic techniques, where reactions that lead to irreversible autoxidation are suppressed. However, at higher temperatures (above 0°C) fast Kinetic... 

Detailed kinetic and mechanistic studies were performed in order to determine the mechanism of dioxygen binding to hemerythrin at the molecular level, and quantum... 

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). 

Mechanisms and rates of dioxygen binding to copper(I) were determined for a series of tripodal complexes that afford end-on superoxo intermediates. Kinetic parameters for a these complexes proved to be rather similar, with activation enthalpies ranging about 3(MK) k.l/mol for reactions in coordinating solvents (nitriles). Activation entropies were relatively small for these processes both small positive and small negative values have been reported.40 This behavior is indicative of... 

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... 

To demonstrate this concept, Krebs and Borovik [21] examined dioxygen binding to immobilized cobalt Schiflf base complexes. The kinetically inert six-coordinate 36 was immobilized into a methacrylate host according to Scheme 14. Complex 36... 

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