Influence of glutathione on the catalytic activity of reconstituted cytochrome P450 3A4

Biochem Biophys Res Commun. 1998 Jan 6;242(1):209-12. doi: 10.1006/bbrc.1997.7861.


The role of NADPH reductase and cytochrome b5 on glutathione (GSH)-induced stimulation of P450 3A4 activity was investigated. GSH increased the Vmax of testosterone 6 beta-hydroxylation without changing the K(m) for testosterone whereas it decreased the K(m) for NADPH-P450 reductase. Addition of cytochrome b5 inhibited testosterone 6 beta-hydroxylation in the reconstituted system, depleting GSH, while it dramatically enhanced the rate of testosterone 6 beta-hydroxylation in the presence of GSH. Cumene hydroperoxide-mediated P450 3A4 activity, which is independent of NADPH-P450 reductase and cytochrome b5, was not affected by GSH. High concentration of GSH above 4 mM was inhibitory in the reconstituted systems. These results suggest that GSH increases the apparent affinity between P450 3A4 and NADPH-P450 reductase, and between P450 3A4 and cytochrome b5, but has no effect on the affinity between P450 3A4 and testosterone.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzene Derivatives / metabolism
  • Cell-Free System
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 Enzyme System / drug effects
  • Cytochrome P-450 Enzyme System / metabolism*
  • Cytochromes b5 / drug effects
  • Cytochromes b5 / metabolism*
  • Glutathione / pharmacology*
  • Hydroxylation
  • Kinetics
  • Mixed Function Oxygenases / drug effects
  • Mixed Function Oxygenases / metabolism*
  • NADH, NADPH Oxidoreductases / drug effects
  • NADH, NADPH Oxidoreductases / metabolism*
  • NADPH-Ferrihemoprotein Reductase
  • Oxidation-Reduction / drug effects
  • Testosterone / metabolism*


  • Benzene Derivatives
  • Testosterone
  • Cytochromes b5
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • CYP3A protein, human
  • Cytochrome P-450 CYP3A
  • NADH, NADPH Oxidoreductases
  • NADPH-Ferrihemoprotein Reductase
  • Glutathione
  • cumene hydroperoxide