The effect of oxygen upon the kinetics of enzyme inactivation: In vitro investigations using glutamine synthetase

Authors

  • Bradley A. Saville,

    Corresponding author
    1. Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 1A4
    • Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 1A4
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  • Steven Persi

    1. Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 1A4
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Abstract

The relationship between enzyme inactivation and the concentration of oxygen in the reaction environment was studied using glutamine synthetase. Batch incubations of the enzyme were conducted under different oxygen partial pressures in a mixed-function oxidase model system. Enzyme activity was monitored using a transferase reaction assay.

Studies showed that oxygen was necessary for inactivation to occur. Furthermore, for oxygen partial pressures up to 61kPa, the rate of inactivation increased linearly with partial pressure. Rates of inactivation ranged from 0.0172+/−0.0038 min-1 at 15 kPa to 0.0591+/−0.0045 min-1 at 61 kPa. However, at partial pressures of 61, 81, and 101 kPa, rates of inactivation were statistically identical.

Abstract

On a étudié la relation entre l'inactivation des enzymes et la concentration d'oxygène dans le contexte de la réction au moyen de synthétase de glutamine. On a réalisé des incubations discontinues de l'enzyme pour différentes pressions partielles d'oxygène dans un système de type oxydase à fonctions mixtes. On a suivi l'activité de l'enzyme par un essai de réaction de transférase.

Les études montrent que l'oxygène est nécessaire pour qu'il y ait inactivation. De plus, pour des pressions partielles d'oxygène allant jusq'à 61 kPa, la vitesse d'inactivation augmente linéairement avec la pression partielle. Les vitesses d'inactivation vont de 0,0172 +/−0,0038 min-1 à 15 kPa à 0,0591 +/−0,0045 min-1 à 61 kPa. Cependant, aux pressions partielles de 61, 81 et 101 kPa, les vitesses d'inactivation s'avèrent statistiquement identiques.

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