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Phosphatase affects microsomal monooxygenase mainly via reductase
Research Communications in Chemical Pathology and Pharmacology
|July 1, 1986
Summary
Alkaline phosphatase treatment significantly reduces liver enzyme activity by inactivating NADPH-cytochrome P-450 reductase. This impacts monooxygenase function without altering cytochrome P-450 levels.
Area of Science:
- Biochemistry
- Enzymology
- Drug Metabolism
Background:
- Hepatic microsomes contain crucial enzymes for drug metabolism.
- Cytochrome P-450 and NADPH-cytochrome P-450 reductase are key components of monooxygenase systems.
Purpose of the Study:
- To investigate the effect of alkaline phosphatase on microsomal monooxygenase activity.
- To determine the specific enzyme responsible for the observed activity changes.
Main Methods:
- Treatment of hepatic microsomes from rabbit, rat, and mouse with alkaline phosphatase.
- Assay of monooxygenase activity (7-ethoxycoumarin-deethylation).
- Measurement of cytochrome P-450 content and NADPH-cytochrome P-450 reductase activity (cytochrome c reduction).
Main Results:
- Alkaline phosphatase treatment markedly decreased specific monooxygenase activity.
- Microsomal cytochrome P-450 content remained unchanged.
- NADPH-cytochrome P-450 reductase activity significantly decreased.
Conclusions:
- The reduction in monooxygenase activity is primarily attributed to the inactivation of NADPH-cytochrome P-450 reductase by alkaline phosphatase.
- Alkaline phosphatase affects the reductase component of the monooxygenase system.