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Distinct pulmonary and hepatic forms of flavin-containing monooxygenase in sheep
D E Williams1, H H Meyer, M S Dutchuk
1Department of Food Science and Technology, Oregon State University, Corvallis 97331.
Abstract:
1. Flavin-containing monooxygenase (FMO) in pulmonary and hepatic microsomes from sheep was analyzed by western blotting by probing with antibodies raised against FMO purified from rabbit lung and pig liver. 2. Pulmonary microsomes from sheep contain a single major protein which cross-reacts with the antibody to rabbit lung FMO, but no band can be observed when probed with the antibody to the pig liver enzyme. Likewise, sheep liver microsomes contain a protein which cross-reacts with the antibody to pig liver FMO, but no significant staining is observed following incubation with antibody to the lung enzyme. 3. Sheep pulmonary and hepatic microsomal FMO also display a difference in activity toward chlorpromazine and n-dodecylamine. 4. Preliminary evidence suggests that sheep FMO may be induced (liver) or repressed (lung) during pregnancy. 5. Sheep are similar to rodents (rat, mouse, guinea pig, hamster and rabbit) in having distinct forms of pulmonary and hepatic FMO. The immunochemical and catalytic difference between sheep liver and lung FMO is similar to that of rabbit.
Insights
Sheep possess distinct flavin-containing monooxygenase (FMO) enzymes in their lungs and livers, differing in protein structure and activity. These findings suggest specialized FMO functions in different sheep organs, similar to rodents.
Area of Science:
- Biochemistry
- Pharmacology
- Comparative Physiology
Background:
- Flavin-containing monooxygenase (FMO) enzymes play crucial roles in the metabolism of xenobiotics and endogenous compounds.
- Distinct FMO isoforms have been identified in various mammalian species, often exhibiting tissue-specific expression and function.
Purpose of the Study:
- To investigate the presence and characteristics of flavin-containing monooxygenase (FMO) in sheep pulmonary and hepatic microsomes.
- To compare the immunochemical and catalytic properties of sheep lung and liver FMOs.
- To determine if sheep FMO expression is altered during pregnancy.
Main Methods:
- Western blotting using antibodies against rabbit lung and pig liver FMO.
- Enzyme activity assays using chlorpromazine and n-dodecylamine as substrates.
- Analysis of FMO expression in sheep during pregnancy.
Main Results:
- Sheep pulmonary microsomes contain an FMO recognized by anti-rabbit lung FMO antibodies, while sheep liver microsomes contain an FMO recognized by anti-pig liver FMO antibodies.
- Distinct immunochemical profiles suggest different FMO forms in sheep lung and liver.
- Catalytic activity assays revealed differences in substrate metabolism between sheep lung and liver FMO.
- Preliminary data indicated potential induction or repression of FMO during pregnancy in sheep.
- Sheep exhibit distinct pulmonary and hepatic FMO forms, similar to rodents and rabbits.
Conclusions:
- Sheep possess distinct flavin-containing monooxygenase (FMO) enzymes in their lungs and livers, differing in immunochemical and catalytic properties.
- These findings highlight tissue-specific FMO expression in sheep, paralleling observations in rodents and rabbits.
- Further research is warranted to elucidate the specific roles and regulation of these distinct FMO isoforms in sheep physiology and drug metabolism.