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Relationship between microsomal hydroxylase and glucuronyltransferase
Advances in Experimental Medicine and Biology
|January 1, 1975
Summary
Liver endoplasmic membranes contain UDP-glucuronosyltransferases and cytochrome P-450 systems. These drug-metabolizing enzymes share inducibility, sex specificity, and inhibition patterns, suggesting a common micro-environment.
Area of Science:
- Biochemistry
- Pharmacology
- Cell Biology
Background:
- The precise number and nature of UDP-glucuronosyltransferases in liver endoplasmic membranes remain unclear.
- UDP-glucuronosyltransferases and the hydroxylating cytochrome P-450 system are key drug-metabolizing enzymes.
Purpose of the Study:
- To investigate the relationship between UDP-glucuronosyltransferases and the cytochrome P-450 enzyme system in liver endoplasmic membranes.
- To compare the properties and behaviors of these two enzyme systems under various conditions.
Main Methods:
- Enzyme activity assays were performed on liver endoplasmic membranes.
- Enzyme solubilization was achieved using sonication and detergents.
- Enzyme properties such as inducibility, sex specificity, and inhibition were examined.
- Effects of solubilization on enzyme activity were assessed.
Main Results:
- UDP-glucuronosyltransferases and cytochrome P-450 systems exhibited similar inducibility, sex specificity, and inhibition profiles.
- Solubilization by sonication or detergents increased UDP-glucuronosyltransferase activity.
- Solubilization decreased hydroxylating system activity, potentially due to loss of essential components like NADPH-dependent reductase.
Conclusions:
- The findings suggest a shared micro-environment, influenced by lipids and proteins, surrounding both UDP-glucuronosyltransferases and cytochrome P-450 enzymes.
- This common micro-environment likely modulates the activity of both drug hydroxylation and glucuronide conjugation pathways.