[PDF][PDF] Modulation of the flavin redox potential as mode of regulation of succinate dehydrogenase activity
M Gutman, F Bonomi, S Pagani, P Cerletti… - … et Biophysica Acta …, 1980 - academia.edu
M Gutman, F Bonomi, S Pagani, P Cerletti, P Kroneck
Biochimica et Biophysica Acta (BBA)-Bioenergetics, 1980•academia.eduThe redox properties of flavin in active and non-active (oxaloacetate reacted) soluble
succinate dehydrogenase were studied. Quantitative analysis of reductive activation
titrations of redox titrations of active and nonactive enzyme reveal that the redox potential of
the histidylflavin in the active enzyme (--3+ 15 mV) is high enough to allow reduction by
succinate, whereas in the non active enzyme it is--196+ 19 mV, far to low to be reduced by
substrate. The flavin radical in the active enzyme attains 60% of total flavin at a poised redox …
succinate dehydrogenase were studied. Quantitative analysis of reductive activation
titrations of redox titrations of active and nonactive enzyme reveal that the redox potential of
the histidylflavin in the active enzyme (--3+ 15 mV) is high enough to allow reduction by
succinate, whereas in the non active enzyme it is--196+ 19 mV, far to low to be reduced by
substrate. The flavin radical in the active enzyme attains 60% of total flavin at a poised redox …
Summary
The redox properties of flavin in active and non-active (oxaloacetate reacted) soluble succinate dehydrogenase were studied. Quantitative analysis of reductive activation titrations of redox titrations of active and nonactive enzyme reveal that the redox potential of the histidylflavin in the active enzyme (--3+ 15 mV) is high enough to allow reduction by succinate, whereas in the non active enzyme it is--196+ 19 mV, far to low to be reduced by substrate.
The flavin radical in the active enzyme attains 60% of total flavin at a poised redox potential of about+ 60 mV, upon addition of oxaloacetate the magnitude of the signal is diminished and the potential where it reaches maximal concentration is shifted by about--200 mV. A mechanism is proposed which ascribes the fundamental difference between active and non-active enzyme to the inability of the latter to be reduced by substrate.
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