Stripping down the mitochondrial cholesterol hydroxylase system, a kinetics study.

The Journal of Biological Chemistry
Burkhard SchifflerR Bernhardt

Abstract

The origin of steroid hormones in mammals is cholesterol that is metabolized by the mitochondrial CYP11A1 system. The cytochrome P450 is fed with reduction equivalents via a small electron transfer chain consisting of NADPH, adrenodoxin reductase, and adrenodoxin. Though the redox behavior of the individual protein components has been studied previously, the kinetics of the system in its entirety has not yet been analyzed. In this study we combine surface plasmon resonance experiments to determine the binding constants for the different pairs of redox partners with measurements of the pre-steady-state kinetics of the different reaction steps of this system and steady-state kinetics. We could correlate the individual protein-protein interactions with the effect of distinct reduction-oxidation steps on the overall catalytic activity of the CYP11A1 system. For the first time, we were able to follow the reduction of each of the protein components of this system within one measurement when we mixed all oxidized protein components with NADPH. These measurements allowed the determination of the individual apparent rate constants for the reduction of all three proteins involved. In addition, variation of the ionic strength in these exp...Continue Reading

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Citations

Dec 15, 2015·Drug Metabolism and Disposition : the Biological Fate of Chemicals·Lina SchifferR Bernhardt
Jun 12, 2010·Biochimica Et Biophysica Acta·Kerstin Maria EwenR Bernhardt
May 5, 2012·IUBMB Life·Kerstin Maria EwenR Bernhardt
Apr 1, 2011·Biomolecular Concepts·Inge Schuster, R Bernhardt
Mar 10, 2015·The Journal of Steroid Biochemistry and Molecular Biology·A MosaR Bernhardt
Mar 7, 2006·Journal of Biotechnology·R Bernhardt
Oct 28, 2005·Journal of Molecular Recognition : JMR·Rebecca L Rich, David G Myszka
Jul 4, 2007·The Journal of Biological Chemistry·Novelle KimmichThomas L Poulos
Sep 28, 2020·Archives of Biochemistry and Biophysics·Stella A ChildF Peter Guengerich

Related Concepts

Adrenodoxin
Metazoa
Biochemistry
Catalysis
Bos indicus
Cholesterol Monooxygenase (Side-Chain-Cleaving)
Fast Electrons
Alkalescens-Dispar Group
Ferredoxin-NADP Reductase
Ions

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